Rav Yaakov Emden says, "By my life, the survival of the Jewish people in this golus is a greater miracle than the Splitting of the Sea"
Where does he says this?
See the introduction to R' Ya'akov Emden's siddur (bottom of the page). R' Emden is continuing from his discussion of the persistent survival of the Jewish people through great adversity and the appropriate conclusions to draw from this regarding HaShem's involvement in the world and His care for the Jewish people:
By the life of my soul! When I contemplated these wonders, they appeared greater to me than all the miracles and wonders that HaShem Yisbarach performed for our forefathers in Egypt, and the wilderness, and the Land of Israel.