I just found this:
Thobyas Lange 1355/83 Halle/S. = Thobe L. 1366 = T. L. 1368/81 = Thobe L. 1368/81, Tobyas 1368/81 Magdeburg = Thobite, auch Thobis
So at least in Germany a few centuries ago there were forms of
Tobias with an initial TH.
This is taken from:
Wilfried Seibicke: Historisches Deutsches Vornamenbuch I-IV, 2000 ff.