if you don't restrict onmyouton, this isn't a fight. Gai nor any of his attacks can get through the stuff, naruto can simply turtle up in the stuff and wait out the 8 gates or use RSM clones that eventually tag Gai with something lethal.
Even if that is restricted though, Naruto would still win considering he's taken no damage so far despite getting hit in the face by JJ Madara's limbou and getting machine-gun punched by kaguya's chakra arms, the later which should be far more powerful than Gai's EE based on Juubito's chakra arms being able to tear the juubi's barrier and the massive shockwave created by a single punch colliding.
Sure Gai is faster than naruto, however unlike madara naruto will be able to keep up due to his speed that's hyped by kaguya and his sensing that madara didn't have (since he was shocked naruto could sense limbo despite saying earlier that he and naruto both had the same rikudou senjutsu).
With rikudou senjutsu kagebunshins, naruto should be able to easily land something lethal like FRS on Gai when he tries to hit a clone or the real as the rest will be free to attack him.
if mindless juubito who was only able to hold 2 gudoudamas at a time can make the shield, I don't understand how Naruto who can manipulate 9 wouldn't be able to make the shield.
As I Mentionned in the first scenario all ninjutsu he has is what has been shown in BM KCM BSM etc guysTruth seeking balls gg