I haven’t done the research, but I would say this industry is much more competitive than hosting and probably a bit more competitive than porn. This is just an opinion mind you, but there are so many terms you can optimize for in the porn industry, where you are restricted down to the number of terms you can optimize for in online gambling. So, from a search perspective it seems logical that it would be easier to get traffic for a porn site that is niche focused. Again, all an opinion, I don’t have any facts to back this up.
As for additional advice on charting a business strategy. The first thing you need to figure out is how to maximize conversions. Meaning, what is the hook for your site that will make people want to click through to an online casino. Throwing up banners and keyword laden copy that is difficult for a person to read through doesn’t help your success rate much IMO. People need to have a reason to be at your site, a reason to click through your site and a reason to come back to your site if you want to be the most successful.
Rev Share is the obvious way to go if your are in it for the long-haul.