A disappointing five-game sequence without a win was ended with a convincing 3-0 win over Crystal Palace on Saturday - an ideal tonic for a return to top flight combat against Steve Bruce's side.
"Yes, sometimes it is important," admitted Gus of the Cup boost. "But we have to realise that we are now going into a Premiership game and we need the points. It is crucial that we change our position in the Premiership as soon as possible.
"We are looking forward to the game, we will concentrate, but have a little bit of a smile because of our last game in the Cup."
The midfielder, who was particularly impressive against Palace before his late dismissal, explains that while quick goals do help fire teams to fine displays, the early period of sparring is a vital spell in a game.
"I think apart from great goals, action and a few moments of very good football, the most important thing for me on the pitch is that we realise what we have to do in the game. On Saturday we set out to show them we were up for the game but, after a few minutes, we just put the ball on the grass and played. That is very important for a team.
"Of course when you have contact with the ball, you pass, you move and you enjoy. You have to run a lot, but when you have the ball you don't suffer."
Gus netted a late winner in the corresponding fixture last season and looks back fondly on his spectacular effort back in April.
"It is a good memory because I remember at the time we were losing a few games. It was at the end of the game and we were not happy at the time having lost the lead.
"When you win a game with a goal in the last few minutes it is always something important and special," he added, before offering his own assessment on the progress of the St Andrews outfit.
"Birmingham is a team that can be very pleased with the way they have been playing probably since after January. I think they changed their game and tried to play differently - even though we know they will apply pressure in midfield.
"They are a good team and will be difficult to play. We have to know what is the right moment to pass the ball around and when to play a little bit more direct."
Meanwhile, skysports.com report that Blues boss Steve Bruce has injury concerns ahead of tonight's game.
Matthew Upson and Stan Lazaridis suffered ankle and groin injuries respectively in Saturday's FA Cup clash with Blackburn which will sideline them for eight and four weeks.
Darren Purse is a candidate to replace Upson but Bruce will have to switch his side around to find a left back replacement for Lazaridis as first choice Jamie Clapham is still out with a hamstring injury.
Christophe Dugarry (knee) is not ready to return but David Dunn is expected to be fit after being substituted as a precaution against Rovers because of his recent calf injury.
Gus Poyet says the team were cheered by the weekend FA Cup victory, but knows Birmingham will prove a tough Premiership proposition at the Lane tonight.