וְהֵפִ֧יץ יְהוָ֛ה אֶתְכֶ֖ם בָּעַמִּ֑ים וְנִשְׁאַרְתֶּם֙ מְתֵ֣י מִסְפָּ֔ר בַּגּוֹיִ֕ם אֲשֶׁ֨ר יְנַהֵ֧ג יְהוָ֛ה אֶתְכֶ֖ם שָֽׁמָּה׃
און גאָט װעט אײַך צעשפּרײטן צװישן די אומות, און איר װעט בלײַבן געצײלטע מענטשן צװישן די פֿעלקער, װאָס גאָט װעט אײַך אַהין אַװעקפֿירן.
Ramban
AND YE SHALL BE LEFT FEW IN NUMBER. He is stating that we will be left as a minority among any of the nations whereto G-d will lead us, for He will scatter us as the four winds of the heaven,94Zechariah 2:10. but in our totality we are many [i.e., Israel will remain a large nation, but because of our dispersion we are in a minority in each of the many countries] — praise be to G-d [that in our totality we are many]!
Tur HaArokh
ונשארתם מתי מספר, “and you will be left few in number.” This is not a reference to the total number of Jews, but a prediction that due to the dispersal of the people in the Diaspora, each host country will have only a small number of Jews. If a census were to be taken of all the Jews in all the various countries, they would still amount to a sizable number.