The way I see it:
Total locations: 22
Total variations: 70
Obviously hardly any of those tracks are confirmed, I simply used the ones from GTPSP, added WRC, NASCAR and SuperGT circuits and the rest of the already confirmed GT5 circuits. Combined with the tracks on the GT5 Prologue weather screen, lo and behold it does come to somewhere around 70. I don't expect they will use all the NASCAR or WRC locations, but there could be a number of other circuits not on this list that we haven't seen yet either. Oh, and some of the fictional tracks are in their countries which were given to them in GT2.