I think the win vs Florida State in week 1 has influenced a lot the idea of the value of Georgia Tech.
Once it is clear that FSU is the main disappointment of the season, GT has no important results left on the calendar. They lost the only two significant games to Syracuse and Louisville.
Duke is nothing special but they are still 5-0 and they won with North Carolina and Connecticut which in my opinion are not less worthy than GT.
Maybe GT is stronger than I think but they still have to prove it. To me this game seems 50-50