More info is needed, and someone familiar with that section for 2018 may be able to comment. Are you a recreational or professional gambler?
You need to first consider what your standard deduction is. What is your filing status--single, married filing jointly, MFS, head of household, etc.? Are you age 65 or older? And/or blind?
How much of the deduction may count may also depend on the amount of your other allowed itemized deductions. i.e., if you have a lot of other itemized deductions, then the gambling deduction would count more.
As for "how much difference", it also depends on your tax bracket. Do you have other income?
In the meantime, here is an article you can review:
<a rel="nofollow" target="_blank" href="https://turbotax.intuit.com/tax-tips/jobs-and-career/can-you-claim-gambling-losses-on-your-taxes/L4lQ3IAWt">https://turbotax.intuit.com/tax-tips/jobs-and-career/can-you-claim-gambling-losses-on-your-taxes/L4lQ3IAWt</a>
Recreational gamblers are not affected by the 2018 changes.
Standard deduction is $12,000 single, $18,000 head of household, and $24,000 married filing jointly.
Add up all your other itemized deductions (charity, state and local income tax and property tax) and see how close you are to the standard deduction for your status. The amount of gambling losses that will actually offset your winnings is the amount over the standard deduction.
For example, if you are single and your itemized deductions would be $6,000, then you would normally take the $12000 standard. When you add $14,000 of gambling losses, that is $20,000 total itemized deductions, which means your new itemized deduction is $8000 more than the standard deduction, that's the amount of winnings that will be offset.
Also be aware that your state may have different rules and different deductions, you might get more or less of an offset on your state return.
Also review IRS pub 529 page 12 for the records that you must have in order to claim gambling losses.
<a rel="nofollow" target="_blank" href="https://www.irs.gov/pub/irs-pdf/p529.pdf">https://www.irs.gov/pub/irs-pdf/p529.pdf</a>
This is a partial quote, but see the Pub for all the record requirements.
"Diary of winnings and losses.
You must keep an accurate diary or similar record of your losses and winnings.
Your diary should contain at least the following information.
- The date and type of your specific wager or wagering activity.
- The name and address or location of the gambling establishment.
- The names of other persons present with you at the gambling establishment.
- The amount(s) you won or lost
Proof of winnings and losses.
In addition to your diary, you should also have other documentation. You can generally prove your winnings and losses through Form W-2G, Certain Gambling Winnings; Form 5754, Statement by Person(s) Receiving Gambling Winnings; wagering tickets; canceled checks; substitute checks; credit records; bank withdrawals; and statements of actual winnings or payment slips provided to you by the gambling establishment."