I'm going to assume you are asking what the difference between a GR and a Newtonian orbital period would be. The Newtonian equation for orbital velocity is v=(Rs×C^2/2R)^.5 and GR is v=[Rs×C^2/2(R-Rs)]^.5 . A distant observer measures the circumference of the orbit as the same in both GR and Newtonian physics. The orbital velocity is higher in GR so the orbital period is shorter/faster. The time dilation is already built into the GR equation.Given an object in a stable close just outside the event horizon of a black hole. To a distant observer, will time dilation make the orbital period appear to be longer/slower than expected by purely Newtonian mechanics?