Do I need to to have receipts to prove gambling losses? I have 4700 of winnings tat are being taxed how do I report losses to counterbalance what I owe?

If you are going to deduct gambling losses, you must have receipts, tickets, statements and documentation such as a diary or similar record of your losses and winnings.

https://www.irs.gov/newsroom/five-important-tips-on-gambling-income-and-losses-1

Yes and no. You do not need receipts at the time you file your  tax return. You will only need them if you are audited by the IRS.

You may only deduct your actual losses, up to $4700 (not more than your winnings) and you may only deduct the losses on schedule A (itemized deductions)/ That is, you must report the full $4700 as income. You may not reduce that amount by losses. The losses go in a separate place on your tax return. If you do not usually itemized deductions (you usually use the standard deduction), you may not see any benefit from deducting losses.