If you fail to pull Gale through the portal, can you recruit him later?
I failed the strength check despite being a paladin and using inspiration. I never saw him again even after getting through nearly all of act 2. I've asked this before, maybe even in this community, but no one gave a concrete answer, likely because the game was still new.
He'll also just stand around near the entrance of the grove on the left side of the road, just past the gate. I didn't even know existed my first playthrough until I was through with the Underdark. Then I read about him online, went back, and found him there.
Only tangentially related, but if you choose to ignore the portal you can come back later to get Gale. I was in a role-playing mood on my first playthrough. When I encountered a strange portal, and was given only the choices of ignoring it or sticking my hand in I thought, "How about no."
That's been the only saving grace is that everyone says he's the most annoying character. A friend even told me they got soft locked because of him and had to reload an older save.
Maybe. I rage quit the first one. Once I get a new PC I might finish and/or play again. Little shit like this is probably one of the biggest reasons I quit. It's absolutely insane to me to lock a follower behind a random chance. I was over 50 hours in before I began to realize I might not see him again. I would've save scummed if I knew.
It's a game that's meant to be played multiple times, since you can't experience everything in one playthrough. I agree it can be frustrating when something gets locked out as easily as a failed roll, and that often causes choice paralysis in myself while I play, but you need to go in with the mindset of not being able to complete everything the first attempt (or you'll go insane).
I hope you can try the game again in the future and enjoy it! Maybe having several plays going at once and save scumming at choice points so you can use the same character for most of the options!