Gambing winning is income, and gambling loss are itemized deduction. You cannot cancel them out directly.
There are a couple of important catches, though. First, unless you're a professional gambler (more on that in a second), you have to itemize in order to deduct gambling losses (itemized deductions are claimed on Schedule A). Since the new tax law basically doubled the standard deduction, most people aren't going to itemize anymore. So if you claim the standard deduction, you're out of luck twice—once for losing your bet and once for not being able to deduct your gambling losses.
