On my W2, box 14 how do I know if New York IRC 414 (h) is subject to New York taxes or is tax exempt? Same question with IRC 125/Sec 18.

All 414(h) retirement contributions that were made pre-tax are tax exempt. (This is most common, but if you are not sure, contact your employer)  Cafeteria contributions that were deducted from your pay pretax are added back to your New York income.

See Public employee 414(h) contributions.