Hey the US is primarily Christian, does that mean if millions of Christians were being forced off their land somewhere we'd open our doors to the refugees? Taking refugees is a lot more complicated than just having the same religion.
You're implying that Gazans can just leave. I'm sure many would if they could but there is literally a wall that they can't go past and nobody has offered safe passage out.
Regarding Arabs settling in Israel: Palestinians are already there; the occupied territories are under Israeli rule for all practical purposes, but the Arab residents are not given equal treatment under the law. This is the core of the problem.