So I know Newcastle are not great, but with Anticipation 16 off the ball 15 and pace 18 Dwight Gayle seems to have the numbers needed to beat offside traps, and yet just about every attack, wht happens, we give away a free kick as Dwight is caught offside, time and time again,
Any advice is much appreciated
Anticipation and Pace are certainly good, however his Off The Ball and Decision attributes are also important, and may be the cause for him jumping off early. It could also be the person supplying the through ball or cross are a bit slow or hold on too long allowing him to run offside. Does the same thing happen with a different striker?
Try changing his role and duty. You haven't mentioned whether he is a lone or part of a strike duo/trio, but a role such as DF's, DLF's, CF's or F9 may help. If DF's doesn't work try DF'd to put him deeper.
In Juventus I put Mandžikić to press the defenders all the time, help the midfield, in all attacking n defensive corners...he get sooner tired and his condition drops, but I still keep him in the game because he is one of the most versatile attackers and MVP.