Like they stopped Obamacare? They will just strip out a bill from the house and fill it with gun control language and deem it passed.
The house has to pass any bill, before it can become law. No revised bill can be made law without passing in the House. So no, a president can’t simply revise a bill that has passed the House and decree it as law. But on the planet Niburu, maybe such things are possible...or maybe in an episode of the X Files.