What do you think about me telling off my friend for his depression?
That sounds bad, what kind of thing would you say to him?
He shouldn't let his depression stop him from living.
I think that's something that your friend might need to hear.  That being said, you need to tell him this, not tell him off.  Friends need to support each other through the tough times.
Dude I don't care if he lives or not.
It seems kind of weird not to care about people you call friends. You will have a more fulfilling life if you have friends that know they can depend on you and that you support them.