You can get about $0.002 Per Unique click per day. This is due to advertisment.
So if you have 1000 people check your livestream per day, every day, so 7000 clicks per week, you can earn $14 from it.
This is of course if you have banners with advertisment. Then also you have the advertisment for 30s before the live stream loads, so another $0.002 for each one of them which loads.
So you could potentionally earn about $0.004~0.006 per unique click per day.
I am guessing they get at least 10,000 unique hits per day, so just from people visiting, and the advertisments loading, a possible $20+ per day just from people visiting their livestream.
EDIT: To all you people saying "Its sad living", I agree but disagree. Its "Easy" living. Income is income. I personally like to graft to earn my money, and i earn alot more then $20 per day. But if you can live on $20 per day, why not sit on your ass and get paid for playing a game. however i could never do this, it personally would take the "fun" out of the game, if im forced to play it all day every day to make a living.