Character Specials Triggering on Non Bang Cards?
In the copy of the rules I've consulted, El Gringo's rules text begins:


  Each time he loses a life point due to
  a card played by another player...


I think it's pretty clear from that that, as long as a card was played that can be held responsible for damaging him, El Gringo's special power will trigger.  Whether or not the damage was "direct".