It's a fair point to say that attendances for mid week cup replays these days are down on league attendances.
We've had 2 in the 2010's 4321 v Eastleigh with 778 travellling and 2955 v Crawley.... it was very cold.
They were both low crowds vs non league opposition at the time, for the Eastleigh game we were sat in a very lowly 21st position in the league which obviously affected that attendance considerably and the Crawley game IIRC it was snowing and bitterly cold, again which would have had a huge impact on the attendance.
There is no doubt that we will not be close to our season average of over 7,200 which is why the club have decided, wisely, to lower the ticket price which could get a few fans back.
We are playing good attractive football and also sat in 1st place with a run of just 2 defeat in the last 8 first team games, 1 was at a higher league opposition who played a full strength side against essentially our reserves and the other was away at Crewe who were top at the time.
There is no doubt the crowd will be less than our average but I think with us being top of the league, a local derby and cheap tickets we will see a crowd of 6,000+ even if Numb bring their usual paltry following for such a short distance of about 400.