Are you blind guys ?
Gai will die anyway. Naruto just spiked a bit of the life fore/chakra in Gai - but just barerly then pulled his arm off either accepting he can not save Gai or it is impossible to Save Gai. The only thing Naruto did is prolonging Gai's life so we will get last words of Gai to Lee and Friends just like Asuma....
Just notice it and stop complaining