Wayne Brightmore, who works for Wil-Tech Electrical Services in Grimsby, said it had been “an amazing season so far”.
He said the club beating Manchester United was “the best night” of his life.
Mr Brightmore, a lifelong supporter and chairman of the Mariners Trust, said, when he walks around the town, he can see more Grimsby tops than ever before.
“Around the town, on social media, anywhere you go, people now have heard of Grimsby Town,” he added.
The match will be the club’s first appearance in the last 16 of the competition for 24 years.
Mick Carr, from Waltham, said he would be taking his wife, Val, to her first game later.
He said: “It’s had a very positive impact on the town. Everybody wants to talk about it. It’s good motivation.
“We’ve beat Man United, so we can beat Brentford.”
