Trump literally just has to throw some insults and jokes out there and he can avoid questions with no backlash. If an insurrection didn’t damage him I don’t know what will, Biden’s issue is his own problem of people seeing him not being mentally sharp in real time so all the smoke and mirror are gone.
There is no real way to undo the damage here. Should people pick him over Trump yes. It is going to be hard when his admin so far has nothing but gain apathy towards him and the only people doing fine are his rich/well off donor base.