They pay market value. Let's say that you come to Netflix with a Facebook offer (or current salary), Netflix wants you, they pay >= FB offer or current salary. If you don't have any offer, they have tech-wide salary surveys that give them a market range for you.
Clearly, nothing is set in stone and a hiring manager can "bet" monetarily on some candidates (i.e., pay them more of what the data points would recommend). When I was there, I was making a (very generous) x and others in my position were making 1.8-2 x no doubt.