American here, I haven’t heard one peep about Trump getting more support because of this outside of Lemmy.
Whether or not the Trump campaign can spin this in their favor depends entirely on the motive of the assassin. If they were just some nutjob, there really isn’t much they can do.
If, on the other hand, the assassination attempt was politically motivated, there are two ways I can see this whole thing being spun:
“The other side knows I’ll win and the only way to stop me is to kill me. If you don’t like them, vote for me because I scare them and they hate me.”
“The other side is so evil and vile they would stoop to try to kill me rather than have a fair election”.
In the event that the assassin wasn’t some flavor of crazy, spin number one is more likely than spin number two, but they’re hardly mutually exclusive.