And conversely, do scholars see any evidence that Plato was familiar with the Torah and incorporated any of it in his philosophy?
On your second question, this is a view called "Neo-Platonism", meaning, attributing the roots of Greek philosophy, and in particular, the views of Plato and Socrates (but others as well), to the teachings of biblical-era figures. On Plato specifically, many Rishonim and Acharonim held the view that his teachings either came from Moshe or from Yirmiyahu or from unnamed Jewish sages.
Plato and Yirmiyahu:
"...and already some have done so, meaning, some of the Greek philosophers admitted to what the prophets said, just as Plato said: "I was with Yirmiyah in Egypt and at first I would mock him and his teachings, and in the end I became accustomed to speaking with him and to doubt his doings and I saw that his teachings were from the Living God, and then I said in my heart that this is all true etc"..."
"...and it was already written in the Moreh La'Moreh by the wise man ben Falqirah of blessed memory that Plato the philosopher...wrote, that he spoke with one of the prophets of Yisrael and in the beginning he was not immensely impressed, but when he delved with him into his Godliness, he was awed and from then it was his goal to understand his teachings. And some say that this was Yirmiyah the Prophet, and indeed he was in the time of Plato, but I don't think he [Plato] was but one of his lesser students."
Abarbanel, commentary on Yirmiyahu 1:6:
"...the text stated early on that Yirmiyahu began prophesying in the days of Yoshiyahu, thirteen years to his rule, and it is an entire verse that he prophesied for forty years as I stated, and after the destruction he went to Egypt and lived there for many years without prophesying until his death, as the rabbi stated, and the Greek wise men bear witness that he spoke with Plato in Egypt..."
Similarly, he writes in Mif'alot Elokim:
"...and this is what Plato the wise man said that the soul moves by itself in a circular motion both when it's in the body and when it's outside of the body, except for the mighty body before it enters it, and if after separating from it and by this motion it gains its freedom and it will know its Creator, and this is a self-caused motion within it and it is whole for all of the days of heaven upon earth [forever]. And indeed this is a scientific notion, seeing as it was suitable that a student such as he be among the students of Yirmiyahu the Prophet, peace be upon him..."
"...and about this matter many have strived but failed, save for Plato who was a student of Yirmiyahu of blessed memory (you shall find this in the book Mif'alot Elokim by the Rabbi Abarbanel...) and on this you shall find that most sages agree that whoever says like Plato's view - this is not apostasy and denial of any part of the religion of Yisrael, and indeed Plato was a student of Yirmiyahu the Prophet peace be upon him, as I wrote above, and hear from him these teachings..."
"[Year] 3385 Plato received wisdom from the prophets and Socrates received from Achitophel and Asaf the Korchite..."
"It is known throughout all the land that Yirmiyah the Prophet, after prophesying for forty years and the Temple was destroyed went to the land of Egypt and lived there for many years until his death and from him Plato received most of his wisdom as the Greek wise men bear witness. And you shall also find that most of his ways are pleasant ways and his paths are paths of peace with the sages of truth and justice...love Plato, love Socrates, but love even more the truth...and Plato too without a doubt heard from Yirmiyahu the Prophet and he kept [the knowledge] and strengthened it fully..."
Rabbi Natan Amram, Noam Ha'Middot:
"...they said about Plato that most of what he said came from the holy books of the sages of Yisrael, and there are those who have proven that he learned much from Baruch ben Neriyah, the student of Yirmiyah the Prophet when he was in Egypt..."
Shlomo Reuven ben David, Bikorei Rosh:
"Therefore it seems to me...that Plato, head of the Greek philosophers was in the time of Yirmiyahu..."
Rabbi Eliyah Lopian in Lev Eliyahu (pt. 1, Shvivei Lev 155) in the name of the Alter of Kelem brings a story in which Yirmiyahu and Plato meet atop the Temple Mount after the destruction:
"After the Temple was destroyed, Plato passed by the Temple Mount and saw the Prophet Yirmiyahu sitting crying and lamenting the destruction. Plato was surprised: "How is it that you, Yirmiyahu the great sage, cries over sticks and stones? What would crying help? After all, it is not becoming for a wise man to cry over what was in the past!"
Yirmiyahu asked him: "Do you have any philosophical problems that you are unable to solve?"
Plato answered: "Certainly. I have many problems that no one in the world is capable of solving them."
Said Yirmiyahu: "Tell me your problems and I'll solve them."
And so it was: Plato told him his problems and Yirmiyahu solved them with ease. Plato was shocked and wondered whether the person before him was mortal, for per his great wisdom he could not have been a mere mortal.
Yirmiyahu said: "You're surprised, but I'm telling you that all of this wisdom I drew from these "sticks and stones"! That's the answer to your first question. As for your second question, how is it that a wise man cries over the past? I cannot answer you because you would not understand the answer."
Plato and Moshe:
"Sophia: "The riddle is beautiful and awesome and there is no reason to think that it does not hint to a wise idea. And since Plato was the author of it, particularly, in that book of his known as Symposium in the name of Aristophanes, therefore, Philo, tell me one of these hints."
Philo: "The riddle comes from an author more ancient than the Greeks, meaning from the holy Torah of Moshe, in the story of the creation of the first human relatives who are Adam and Chavah."
Sophia: "I have never heard Moshe say anything like this."
Philo: "He did not say this exact thing with these exact details, but he did leave the main concept and Plato received from him and expanded upon this nicely, as is customary by the Greeks and made this into a more complicated work than the teachings of the Hebrew.""
Plato and unnamed prophets:
The Remah's notes on Sefer Yochasin by Rabbi Avraham Zaccuto:
"I found it written that Plato received his wisdom from the Prophets. And Socrates received from Achitophel and from Asaf the Korchite."
1 There are much earlier Christian sources, but I am of the opinion that this was originally a Jewish idea/tradition that was lost to Jews but preserved by Christians. There are several examples of such lost traditions that can be found within the writings of the early Christians. We then merited to have it re-surface in the time of the Rishonim.
Note Rambam in Moreh Nevuchim (Guide for the Perplexed) Part 2 6:3:
ודברינו הנה אמנם הוא ב'מלאכים' אשר הם שכלים נפרדים שתורתנו לא תכחיש היותו ית' מנהיג זה המציאות באמצעות ה'מלאכים'. וכתבו ה'חכמים' במאמר התורה "נעשה אדם בצלמנו" ואמרו "הבה נרדה" (אשר זה 'לשון רבים') - אמרו "כביכול שאין הקב"ה עושה דבר עד שמסתכל בפמליא של מעלה". והתמה מאמרם 'מסתכל' - כי בזה הלשון בעצמו יאמר אפלטון שהאלוה יעין בעולם השכלים וישפיע ממנו המציאות. ובמקומו אמרו כן מחלט "אין הקב"ה עושה דבר עד שנמלך בפמליא של מעלה" - ו'פמליא' הוא המחנה בלשון יון. וב'בראשית רבה' גם כן נאמר וב'מדרש קהלת' "את אשר כבר עשוהו" - 'עשהו' לא נאמר אלא 'עשוהו' כביכול הוא ובית דינו נמנו על כל אבר ואבר שבך והושיבו אותו על כנו שנאמר "הוא עשך ויכוננך". וב'בראשית רבה' גם כן אמרו "כל מקום שנאמר וה' - הוא ובית דינו": ואין הכונה באלו המאמרים כולם מה שיחשבוהו הפתאיים שיש לו ית' דברים או מחשבה או התבוננות אל שאלת עצה והעזר בדעת אחרים
When we assert that Scripture teaches that God rules this world through angels, we mean such angels as are identical with the Intelligences. In some passages the plural is used of God, e.g., "Let us make man in our image" (Gen. 1:26); "Go to, let us go down, and there confound their language" (ibid. 11:7). Our Sages explain this in the following manner: God, as it were, does nothing without contemplating the host above. I wonder at the expression "contemplating," which is the very expression used by Plato: God, as it were, "contemplates the world of ideals, and thus produces the existing beings." In other passages our Sages expressed it more decidedly: "God does nothing without consulting the host above" (the word familia, used in the original, is a Greek noun, and signifies "host"). On the words, "what they have already made" (Eccles. 2:12), the following remark is made in Bereshit Rabba and in Midrash Koheleth: "It is not said 'what He has made,' but 'what they have made'; hence we infer that He, as it were, with His court, have agreed upon the form of each of the limbs of man before placing it in its position, as it is said, 'He hath made thee and established thee'" (Deut. 32:6). In Bereshit Rabba (chap. li.) it is also stated, that wherever the term "and the Lord" occurred in Scripture, the Lord with His court is to be understood. These passages do not convey the idea that God spoke, thought, reflected, or that He consulted and employed the opinion of other beings, as ignorant persons have believed. (Sefaria translation)
The Kuzari 4:40 writes:
אָמַר הֶחָבֵר: הֱטִיבוֹתָ מֶלֶךְ כּוּזָר! זֶהוּ הָאֱמֶת וְהָאֱמוּנָה בֶאֱמֶת וְעֲזִיבַת מַה שֶּׁאֵין צֹרֶךְ אֵלָיו. אַךְ שֶׁמָּא הָיָה זֶה הָעִיוּן מֵאַבְרָהָם אָבִינוּ כְּשֶׁנִּתְבָּרְרָה לוֹ הָאֱלֹהוּת וְהָאַחֲדוּת קֹדֶם שֶׁיְדַבֵּר עִמּוֹ בְּמַחֲזֶה, וְאַחַר שֶׁדִּבֶּר עִמּוֹ הִנִּיחַ כָּל הַקָּשׁוֹתָיו וְשָׁב לְבַקֵּשׁ רְצוֹן הָאֱלֹהִים מֵעִמּוֹ אַחַר שֶׁלִמְּדוֹ, וְאֵיךְ הוּא הָרָצוֹן וּבְאֵיזֶה דָבָר יֻשַּׂג וּבְאֵיזֶה מָקוֹם. וּכְבָר דָּרְשׁוּ רַבּוֹתֵינוּ: בְּ, וַיּוֹצֵא אוֹתוֹ הַחוּצָה', 'צֵא מֵאִצְטַגְנִינוּת שֶׁלָּךְ' ר"ל: צֵא מֵחָכְמַת הַכּוֹכָבִים וּמִכָּל חָכְמָה טִבְעִית מְסֻפֶּקֶת. וּכְבָר אָמַר אַפְלָטוֹן מֵהַנָּבִיא שֶׁהָיָה בִזְמַן מָרִינוּס הַמֶּלֶךְ, שֶׁהוּא אָמַר לְפִילוֹסוֹף שֶׁהָיָה מִתְעַסֵּק בְּפִילוֹסוֹפִיָה, בְּחָזוֹן מֵהָאֱלֹהִים:"לֹא תַגִּיעַ אֵלַי בִּדְרָכִים הָאֵלֶּה, אַךְ בְּמִי שֶׁשַּׂמְתִּיו שָׁלִיחַ בֵּינִי וּבֵין בְּרוּאַי, רְצוֹנוֹ לוֹמַר: הַנְּבִיאִים וְהַתּוֹרוֹת הָאֲמִּיתִיּוֹת".
The Rabbi: Just so, O King of the Khazars, by God! This is the truth, the real faith, and everything else may be abandoned. Perhaps this was Abraham's point of view when divine power and unity dawned upon him prior to the revelation accorded to him. As soon as this took place, he gave up all his speculations and only strove to gain favour of God, having ascertained what this was and how and where it could be obtained. The Sages explain the words: 'And he brought him forth abroad' (Genesis 15), thus: Give up thy horoscopy! This means: Forsake astrology as well as any other doubtful study of nature. Plato relates that a prophet, who lived at the time of the king Morinus, said prophetically to a philosopher who was zealously devoted to his art: Thou canst not reach me on this road, but only those whom I have placed as intermediaries between me and mankind, viz. the prophets and the true law.
Rav Yosef Albo in his Sefer HaIkarrim when exploring Divine law vs conventional law notes as follows:
ויתבאר מזה שאי אפשר לשום מסדר נימוס אנושי שלא יטה בטבעו לצד איזה פחיתות, וישפוט על הנאה שהוא מגונה ועל המגונה שהוא נאה, ולזה לא יהיה עדותו על הנאה והמגונה אמת. הלא תראה כי אפלטון טעה בזה טעות גדולה ואמר על המגונה שהוא נאה, כי אמר שראוי שיהיו הנשים במדינה משותפות לבעלי ראשיות אחת, כאלו תאמר נשי השרים משותפות לכל השרים ונשי הסוחרים לכל הסוחרים, וכן נשי בני אומנות אחת משותפות לכל בני האומנות ההיא, וזה דבר הרחיקה אותו התורה, ואפילו תורת בני נח, שהרי נאמר לאבימלך הנך מת על האשה אשר לקחת והיא בעולת בעל, והוא התנצל בשלא ידע שהיתה אשת איש. וכבר גנה אריסטו דעת אפלטון בזה.
It becomes clear now that it is impossible for any author of a human code not to show a natural deficiency in some direction, and regard the becoming as unbecoming and the unbecoming as becoming. His testimony concerning the becoming and the unbecoming will therefore not be true. Thus Plato made a grievous mistake, advocating the unbecoming as though it were becoming. For his idea is that all the women of a given class should be held in common by the men of that class. Thus, the wives of the rulers should be common to all the rulers, the wives of the merchants common to all the merchants, and similarly the wives of the men of a given trade or occupation should be common to the men of that trade or occupation. This is a matter which the Torah forbids; even the Noachian law prohibits it, for Abimelech was told, Behold, thou shalt die, because of the woman whom thou hast taken; for she is a man’s wife, and his excuse was that he did not know she had a husband. Aristotle, as is known, criticized Plato’s idea in this matter. (Sefaria translation)