Ever since I discovered the Brave series, I've had this suspicion that Might Guy's name was taken from the first names of 2 protagonists in 2 different entries of it, Might Gaine and GaoGaiGar (the 4th and 8th entries respectively).
The names of the protagonists in straight romanization are Maito Senpuuji and Gai Shishioh.
What they have in common aside being from this metaseries is that they're both voiced by Nobuyuki Hiyama (though Might Guy himself is not).
And they both fit the Super Robot archetype of hot-blooded protagonist (Might Guy himself is pretty much this trope and exemplifies it the best throughout the series more than anyone else).
And since we know Kishimoto is no stranger to mecha given his references to the likes of Gundam, Raideen, Mazinger Z, Jeeg, and more, this makes sense doesn't it?