Amazon entry level software engineer in Seattle starts at over 100k and senior goes way up from there. Particularly with the stock gains of AMZN, engineers are highly compensated.

Not compared to FNG. A big reason for this discrepancy is enforceable noncompetes in Washington. In California, poaching is always fair game, so employers that compete on compensation have to pay accordingly.

What are your sources? Mine are I work for Facebook and worked at Amazon 8 years.

If you come from Amazon, Facebook will make an offer accordingly. If you have competing offers from NG, you will get a significant bump during salary negotiation. My sources are offers from these companies for multiple engineers.