He doesn't. At the end of Bainlings he says he doesn't even have the money to hire one.

I thought he mentioned that justin.tv provided him with it

What method are you using to determine he is the 'top' caster?

Of all popular casters out there, he is the least professional and least insightful.

# of views?

Rumors puts popular casters at around 250K a year, just from youtube revenue.

Pretty impressive. Much of this money likely goes to further tournaments and such anyways so a lot of the money is probably finding its way back to players.

They also spend their money making videos like this: http://www.youtube.com/watch?v=fzMhh8zhTiY

He really looks like he's having fun.