Using his eye, Sasuke can shift himself, others, and objects, a set distance away from his original location. He can increase the range of this technique by
instantaneously changing place with a remote space,
You must be registered for see links
This is obviously superior to Gai's speed by far due to the simple fact that Gai's speed is not instantaneous like Amenotejikara. Sasuke could easily blitz Gai with Ameno, possibly ending it with Rikudou chakra Chidori Variants that
You must be registered for see links
). Reaction speed would be a variable in this case had Sasuke not possessed Amenotejikara, which he would apply in a scenario like this; Sasuke uses chidori, and thrust into a blank space prior to appearing in front of Gai using Ameno with a chidori attack already in motion. Gai's Eight Gate arsenal would also play a factor in this match, if Gai could so much as touch Sasuke. While there is no prerequisite for using the technique, it does have a recharging period after each use. However,
You must be registered for see links
Conclusion: Sasuke blitz and negs Gai.