Whenever someone falls and enter bleeding state, the player becomes imortal until he's revived, he doesnt even die from /kill and has to "give up" or wait until the timer runs out.

Is there a way to make it so, he can actually be killed by other players or lava during bleeding state?

In the newer versions there are settings to change that. Use the command /cmdconfig and go through the bleeding config.

Even when doing so, i'm still imortal, I don't know which stat to change

What mods do you have installed? What PlayerRevive version do you have installed?