Interesting, I've not had more than the usual waves of tentacles. I did notice on some runs, I got the tentacles spawned before I cleared the older ones, but figured that was because I dealt with the ambushes.
Sounds like the easiest test on this would be to clear the ToV, and take out most of the tentacles. Then hang out to see if they keep respawning tentacles.
If they aren't infinite, and I doubt they are, some reward for the dang things would be nice. It annoyed me when I noted they had no reward.