How much does a Senior UX Designer/Product Designer make at Google/Microsoft/Facebook make?

Anything from 200-500

At Microsoft in Seattle, Senior starts at level 63 (up to 64). Starting salary for 63 is around $150k, avg annual cash bonus is 15%, avg annual stocks around $22k... so around 200 TC (not including sign on cash/stock). If you consider 64, high reviews (30%), special stock awards, you're looking much higher.