Considering the insane amounts of traffic they get and the kinds of ads they serve, I'd be hard pressed to believe they weren't making a small fortune.
this is pure speculation, but since we're down that road anyway: The Pirate Bay has hosting in quite a few places, but many of them are in Europe where you pay a good premium for bandwidth. Yes, they have some good advertising contracts but I'd be very surprised if it didn't eat up just about what it makes.
The reason for this is that I think their user demographics are shifted towards people that do not really want to pay for content ;)