If you are asking about the volunteer firefighters' credit (which is the only firefighters credit available on an NY state income tax return) it is under the "Take a look at New York credits and taxes" section when you are working on your NY state income tax return (screenshot).
Here is some additional information about this credit:
The volunteer firefighters' and ambulance workers' credit is available to full-year New York State residents who are active volunteer firefighters or volunteer ambulance workers for the entire tax year for which the credit is claimed. If the credit exceeds your tax for the year, any excess will be refunded without interest. For additional information and qualifications, please click on "learn more" next to the credit in TurboTax.
