I think that it is just a coincidence that some of the images of Christ look like Cesare Borgia.
If you look at the pictures below, there is a definite resemblance between the second Christ image and that of Cesare Borgia. However, that particular
picture of Christ was created in the late 6th century.
The first one was painted in the 12th Century and is included in order to prove that icons of a 'white christ' were in existance well before the
birth of Cesare Borgia (September, 1475 - March 12, 1507).
It is possible that the later (Renaissance) images of Christ were painted to resemble Borgia, probably due to artists trying to flatter the pope (who
was a patron of many artists).
Christ the Savior.
Russia. Mid. XII-th century.
Christ the Savior.
Sinay. Monastery of St. Catherine.
Enaustic icon of late VI-th century.
Cesare Borgia