I am not sure but I do know that gambling winnings are taxed differently than regular income. If you are a poker pro you can list your winnings as earnings. They have sued the government for this right. They then can also deduct travel expenses and other expenses related to their poker playing. Either way, remember that you might also have to pay the FICA taxes on the winnings. If the amount is significant you may want to seek a tax preparer. If it is a relative small amount, you could buy a tax prep software like H&R Block at Home (which I use). It will prompt you for gambling winnings.
Yes you can deduct the entry fees, you can even deduct all gambling losses up to the amount you won. You can't deduct more gambling losses than what you have won though. That is why I never throw away non-winning lotto tickets. I even pick-up and save any ones I find laying around at the store.
Hope this has helped.