Trump has talked about gun control - comprehensive background checks and the like - in the past and has been talked out of it by pointing out just how unpopular such steps would be with is base. Cruz is reminding the President of that basic fact. If Cruz doesn't do it then others must.
Trump talks about a lot of things. You can’t listen to what he says, you must watch what he does. I would have thought people understood that by now.
He’s been talked out of things? That sounds like either Lindsay Graham talking (for what that’s worth) or you hang on the mainstream media’s rumor-mongering too much.