Can i use my gambling losses on a 1040 to reduce my 1099 winnings?

Gambling losses can only be deducted up to the amount of the gambling winnings.  Gambling winnings are reported on Form 1040 Schedule 1 on Line 21 as Other Income.  Gambling Losses are reported on Form 1040 Schedule A as a Miscellaneous itemized deduction.  Gambling losses are not a one-for-one reduction in winnings.  Your total itemized deductions reported on Form 1040 Schedule A must be greater than the standard deduction for your filing status to have any tax benefit.

To enter, edit or delete Gambling Winnings and Losses -

• Click on Federal Taxes (Personal using Home and Business)
• Click on Wages and Income (Personal Income using Home and Business)
• Click on I'll choose what I work on (if shown)
• Scroll down to Less Common Income
• On Gambling Winnings, click the start or update button

Or enter gambling winnings on w-2g in the Search box in the upper right of the program screen.  Click on Jump to gambling winnings on w-2g

please be aware, that unless your itemized deductions exceed your standard deduction, entering gambling losses will not change your taxes.