Interestingly though gambling sites still only pay, at best, about half the rev share I've heard porn sites pay their top affiliates. I was one of a few poker sites' largest (generating them hundreds of thousands in rev monthly) and got somewhere between 35 and 40 percent typically. From what I heard from my friends in the financial industry, in porn you can get 85% if you're large enough.
It's baffling to me that a company that serves up web video can make serious profits even while giving 85% of their revenue away.
Now my revenues and margins are considerably smaller than they were back then. I could maybe, with full time effort over a long period, have rebuilt, but I didn't bother because of the general instability of the industry. I'll pass the opportunity to get on a soap box about our government's stupidity here, but suffice it to say the Bush DoJ (and maybe Obama's too, not sure yet) made the business seem a less worthwhile investment than something not in such a legal minefield.
I used to send some traffic to a Bingo website, and I think you got £25 per signup, but then 50% of all future losses for the lifetime of that player. After only a couple of months that revenue share (%loss) was making up hundreds of £/month for doing nothing. I'm sure it's pretty similar for paid porn sites.
They'd have to be doing something seriously wrong to be losing money in that sector.