Aside from the fact that she won’t give up, voting has begun with the Felon as the candidate. If Hillary quits, it’s over. Trump wins.
If she agreed to step down, all the votes for her ticket would still count on election day and count toward selecting electors for the Democrats. Then those electors can be instructed to vote for the replacement candidate when the electoral college votes, and in most cases they would be party loyalists who would comply.