It's the same Grand Inquisitor, they've already told us it is. It'd be stupid to replace him with an almost identical character, super dumb.I am not sure, but I think some of them were also other Force-sensitive children taken in by the empire.
On a side-note, I do not think the Grand Inquisitor here is the same one from Rebels. Maybe the one that replaces this dead one is the one from Rebels.
Pau'an have two stomachs, he'll be fine.