If the gambling losses are less than your NY standard deduction, it will be better to use the standard deduction than the itemized deduction.
It appears that, on the NY IT-203 non-resident return, you are entitled to the full NY itemized deduction, and not a reduced or pro-rated amount. (Although this surprises me.)
https://www.tax.ny.gov/forms/current-forms/it/it203i.htm
@TomD8 ??
New York State standard deduction table
| Filing status |
Standard deduction (enter on line 33) |
| (1) Single and you marked item C Yes |
$3,100 |
| (1) Single and you marked item C No |
$8,000 |
| (2) Married filing joint return |
$16,050 |
| (3) Married filing separate return |
$8,000 |
| (4) Head of household (with qualifying person) |
$11,200 |
| (5) Qualifying surviving spouse |
$16,050 |
