Gai surviving would be an insult to his character, having him go on a suicide plunge towards one of the strongest Shinobi to ever exist to protect the ones he loves, willing to sacrifice his life, and being saved? No. That's insulting.
its not about will her die or not he will die...that gate is around his heart and he is sweating all his blood into the vapor in the air...he even said he is under lots of pain idk if he can be healed from such a technique
it would be bad writing if gai survives .. however.. for gai to know the techniques of 8th gate means that someone had to have already entered 8th gate and survived in order to pass on what the 8th gate is like..
Since Gaara was revived well after he died, and that Obito survived the extraction of the Bijuu which then was explained that the Gedo Mazou's shell was the reason, which then it was extracted yet he still didn't die, I would say that there is no denying the chance that Gai could survive somehow with a combination of healing jutsu and huge life force given to him somehow.
However, the way the manga is going, it's pretty clear he's going to die (and stay dead).