Traditionally it is pronounced as in Latin (YEH-zoo), but as
this text is not the original I see no problem with singing it
however you see fit; I have even heard the first word changed to
"Jesus," which does make more sense than using Latin. The original
text is "Jesus bleibet meine Freude" and the movement is taken from
Bach's cantata BWV 147 "Herz und Mund und Tat und Leben."