Sure, although the mixture of spices in pumpkin pie spice is not an exact match (pumpkin pie spice sometimes includes allspice), it’s fine to replace the spices in the scones and glaze with pumpkin pie spice. Just replace the individual spices with an equal amount of pumpkin pie spice, so in this case, you’ll need 1 tablespoon for the scones and 1 teaspoon for the glaze.