wikipedia says 1,5 million arabs for the westbank. Now many of them might be christian and not muslim, but still, I don't see why judaism would be the majority.
I still don't get it... there are MANY jews living in the westbank, but "MOST of the west bank" is arabic and muslim, and there are even more and more muslims living there. Also, how the jewish settlements will develop once the arab state is declared is not clear; in any case the jews there are outnumbered
But the majority religion in Judea and Samaria (West Bank) and the Golan Heights is Judaism.
And if a Palestinian state will be recognized by the UN, they have no power in setting borders without the peace and agreement of Israel.