Prey 2 does use id Tech but doesn't use id Tech 5.
Bethesda mouthpiece Pete Hines told IGN that the game was started too long ago to use id Software's latest and greatest engine - the thing what powers Rage.
"This game has been in development for quite a while and id Tech 5 is still in progress (until Rage ships, and probably even after). So it really wasn't an option," he explained.
Bethesda was announced as the publisher of Prey 2 yesterday. The press release misleadingly informed that Prey 2 was "being built on the cutting edge id Tech engine from id Software".
Like Brink, Prey 2 uses an older id Tech engine (presumably id Tech 4). Brink developer Splash Damage has heavily modified the engine, though.
Prey 1 developer Human Head will make Prey 2, which has a 2012 date with PC, PS3 and Xbox 360.