The 23-year-old is involved in a lengthy contract wrangle with the north London club, expressing his desire to play centrally instead of out wide as a condition of staying at the Emirates Stadium.
And the Frenchman noted that the England international had done his chances no harm with his finishing on Wednesday evening.
"[Walcott] is a great finisher now. In front of goal he is absolutely amazing," Wenger told reporters.
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"I'm not against [playing Walcott through the middle] at all."
Wenger also expressed his delight at Olivier Giroud netting his first goal for the club since his summer move from Montpellier.
"It was in everybody's mind and a case of the sooner he gets it the better," he observed. "It was more in his mind than in ours. It's a positive.
"He's a good finisher but at the moment I believe he is looking for confidence and that will help him."
The 62-year-old went on to praise playmaker Andrey Arshavin as the Russian impressed, making his first start for the club since January.
"His best position looks to be behind the striker now. That's where his vision and creative side of game becomes most efficient," Wenger mused.
"When he works on the flank it sometimes works against him as he has to work up and down. When he is central, he can influence the game.
"We did our job," the Gunners manager added of the win as a whole. "In the first half we were tested defensively but in the second half our offensive potential made the difference. We were always a threat and that made a big difference," he said.
"It was a classic cup tie. We needed to be serious and we were."