The companies advertising in places like this are usually not exactly the ones with a legit business address and a great track record of being transparent.
The money made from ads is probably a lot less than the ad revenue you know from other places, there are a lot of middlemen, ad networks, and money services involved and everyones takes their cut.
The advertiser might be willing to put down his name, but what about the person/persons on the other end. No one knows who is running TPB at this time, nor where the servers are. If that information would leak through paper-trails, you can be sure legal actions would be sent their way by a number of anti-piracy groups. Questions about taxes and damages could also pop up depending on whom is running TPB and from where.
The money made from ads is probably a lot less than the ad revenue you know from other places, there are a lot of middlemen, ad networks, and money services involved and everyones takes their cut.