I would be careful saying Trump's bounce from a -25% approval to -20% is due to his response when it was probably regression to the norm after his health care slump.
I would also say thinking some Republican who already lost statewide once could win in a state Trump lost and has a -20% or lower approval rating is delusion.
I definitely agree that Gillespie must wage an uphill battle if he wants to be Governor, and that Northam will be the likely victor of this race barring a major development in Gillespie's favor. I would caution, however, that earlier posters have concluded that Gillespie looks and sounds a lot better than Northam in a debate.
He has, however, not been hurt by the events of the past week if the statistics are to be believed.
Regarding your first point, you are probably right.