It's hard to say exactly. I know our locals usually give about 100-300 bucks for singles, and usually about 2/3 for teams. Sometimes those happen every other weekend, other times we can go about a month without having any. A top player can (and around here, does) always win those.
Mango got ~2500? for Evo, and PP got 5200 for Apex. Big tournaments have pretty varying pot sizes/bonuses. Of course, even for the elite they can find themselves placing down to 7th or 9th sometimes. There are usually a few big tournaments a year.
You also have to take out travel costs, since there's a plane ticket involved in many cases. It's hard to gauge with any sort of certainty. If I had to guess I'd say the top 5 probably make enough to call it a living, but not enough that it would be a salary to get excited about.
That doesn't even consider sponsorship. I have no idea how that all works.
Regardless of how much they make, it must be nice to get payed to travel and compete. There are plenty of scrubs like me that go out to these things and only ever lose money.