The way I see it, it is Ponyboy who is comparing Dallas Winston to the Southern gentlemen like the ones in Gone with the Wind. He does this on p. 168 in my book -- the part just after Johnny has died and Pony has been told that Johnny has left him his copy of Gone with the Wind.
What Pony says is that the gentlemen from the South would go riding into battle even though they were certain to die. He says that they would do it because they were gallant. He sees Dally's death in a similar way. He imagines Dally like this, and he does not want to think about it any more.