I agree with what Dom said. But there are a few companies around who are very very good at SEO – The thing is though they charge an absolute fortune – At least well into 5 figures a month easily. Hence the only people that can afford them are the casinos themselves.
Bear in mind that it will take a good 6 – 12 months before you see any results as well, especially if it is a new site and you want to rank in google. By that time you could well have spent over $/£ 100k without a return.
Check out seochat.com, webmasters world, check the archive threads on this forum and be prepared to do a lot of reading. This industry is not easy and you will have to put in a lot of work, 7 days a week for a couple of years before you start seeing some progress.
Sorry to be negative.