Voltaire would not have approved of the Immigration ban, per evidence of the quote from his primary source "A Plea for Reason and Tolerance" saying
"I will go even further as to say that we aught to view all men as our brothers"
Voltaire does not think that some people are better than others but that we should view everyone as equals, and that we should view all men as our brothers. He explains
What! call a Turk, a Jew, a Siamese my brother? Yes of course!
Voltaire would not have been for the immigration ban per evidence of his primary source and his statement saying that everyone should be viewed as an equal