The ballots cast so far are more Democrat than Republican with a very large cohort of independents. 54/46 women to men. But the average age of the voters who have returned ballots so far is 59. There is no way the pro-gay side is going to win with an average voting age of 59. This is the nature of very low turnout off-elections: the gnarled hands of the elderly steer the ship.
If the pro-gay side can get more than 40%, I'd call that a sign of real progress in the Bible belt. If they can get into the mid-40s, that would be a victory. Remember that most of the southern states passed their amendments by margins exceeding 70% just a few years ago and a few surpassed 80%. Only 1 southern state came in under 60% and that was in purple-ized Virginia on a general election day in a very democratic year. If the more solidly conservative NC comes in below 60% in a low-turnout off-election with an elderly electorate, it is no spin to call that a kind of a win.