Every page of your website is an entry point to your site, so yes the more pages you have, the more traffic you get. Content is also very important as it provides information to the search engines for what your site is about. The more information you provide, the better the search engine can figure out where to rank your site. That’s half the equation anyway, backlinks are the next important thing.
As for your keywords, “casino bonus, free bonus” those are about the worst words you could choose IMO. There are so many bonus chasers and bonus abusers out on the web that you would end up with a lot of fraudulent players whether you intended to or not. Many of the other players will just play until the bonus conditions are met and move on, providing little long-term revenue.