I'm starting him, but won't be surprised if his output disappoints.
Regardless, when in doubt, I always default to the "always start your studs" approach, even if the matchup looks bad or dicey. I've found that, at least for me, that is the approach that provides the most peace of mind.
Update/ ETA: Rotoworld is now reporting that Gronk will be on a snap count, presumably rotating with Bennett.