Chakra is Ki,
the gates limit how much chakra flows through it

So....this leads me to believe that he just fucked up terms. What do you think? I personally never heard of things like Life gate, Forest gate, and Insanity Gate in all my years of martial art studies, have any of you?
It wouldn't really matter, he could've made it up to how he wanted, and you'd still have to believe it for his story.

and there isn't a Forest or Insanity Gate in Naruto.