in pennsylvania does an employer have to pay a terminated employee earned vacation pay

Your prior employer has to pay you for any accrued paid time-off in accordance with their policies for handling paid time off. Some employers provide that PTO is paid after termination if termination is not for certain types of reasons (employee theft, etc.), others provide that no PTO is paid, regardless of the reason for termination.

If under the employer's policy for PTO you would have been entitled to the PTO, then the employer must pay you within two weeks of the last pay period following your termination or it is a violation of the PA Wage Payment Collection Law.