In fact even apostles gambled when they need to chose successor of Judas Iscariot. Not to mention many times people gambled in Old Testament.
The only thing The Bible say for sure is: to not fell in love with money and lose yourself in greed.
To be more specific the Bible says in 1 Timothy 6:10, "For the love of money is a root of all sorts of evil, and some by longing for it have wandered away from the faith and pierced themselves with many griefs." The Bible doesn't say that money is evil, or that gambling is a sin, but it does say that the love of money is the root of evil. If pursing money consumes you and becomes an idol, it is a sin.