Danny Graham scored a late equaliser to send the tie to a replay, but despite his frustration at a "missed opportunity" Wenger was delighted with Gibbs' performance.
"It was a fantastic strike," the manager told Arsenal Player. "I am happy that he scored because you feel there is a lot more coming out of Kieran.
"He does not always have belief in his finishing, and today it was there and I hope it will convince him that when he gets in these kinds of positions he can take his chance.
"[The match] is a missed opportunity because I felt we played well and created many chances. When you look at how busy their keeper was and how busy our keeper was it is frustrating [not to win].
"It can happen that you concede a goal but I felt we lacked concentration on the corner. You didn't feel any urgency. It is down to nervousness and we were not calm and focused.
"But we have shown character and quality and those are good ingredients for the coming weeks."