When kakashi and Gai were up against 6 tailed beast i think it was. Gai said he would open the 8th gate so kakashi could get out of it alive....if the 8th gate is strong enough to atleast hold off 6 tailed beast at the same time, maybe beat them idk, dont you think he could kill any ninja in naruto?...even tho he would die from the 8th gate...