The IRS does not permit you to simply subtract your losses from your winnings and report your net profit or loss. And if you have a particularly unlucky year, you cannot just deduct your losses without reporting any winnings. If the IRS allowed this, then it's essentially subsidizing taxpayer gambling. The bottom line is that losing money at a casino or the race track does not by itself reduce your tax bill. You need to first owe tax on winnings before a loss deduction is available. Therefore, at best, deducting your losses allows you to avoid paying tax on your winnings, but nothing more.
That last sentence from Turbo Tax is the most important. Gambling tax deductions essentially just offset winnings. For this writer, the best way to look at taxes is to really hope that I have to pay because that means I won more than I lost. Like all taxes, gambling taxes aren't simple and it's always recommended that you talk to a professional.
All casinos offer win/loss statements for your taxes so if you haven't received an email reminder, check your players club website(s) and you will see this year's forms when they're ready.