The 23-year-old has scored five goals in 12 appearances in all competitions this season and, despite only making three Premier League starts so far, Wenger is confident he will continue to make an impact for the club.
He said: “I feel that before (Alex) looked nervous when he was in front of the goal and now we hope that he will continue to go forward and this will build his confidence.
“He has been working really hard in training. That is now showing on the pitch.
“His concentration and his focus have improved, he is much sharper and he will continue to do well.
“(To start games in the Premier League) he needs to keep playing like that.”
Arsenal made nine changes from their 0-0 draw with Middlesbrough in the Premier League on Saturday and Wenger believes that enjoying a good cup run is great for the players that are struggling to break into the starting XI.
He said: “I think that the players did well. I felt Rob (Holding) did well, Ainsley (Maitland-Niles) played some nice passes and Jeff (Reine-Adelaide) had a good game too.
“If you are still in all the competitions it is not to hard (to give the whole squad a game).
“That is a positive of the result here, when the players win they gain confidence and they know they will get a game.
“We have three top goalkeepers and (Emiliano Martinez) knows he will get a game if we win. It is a good incentive.”