Havertz, after suffering a knee injury in the opening game of the season, made his return as a second-half substitute in the FA Cup win against Portsmouth.
Ahead of tonight's Carabao Cup semifinal first-leg against Chelsea, Arteta said: "Obviously we missed him a lot. A year is a long time in football but as you said, the way he’s come back, he looks really fit, really confident.
"He’s such an intelligent player that straight away he is someone who connects with the players really naturally, and you can tell how much they love him as well, because every time he was in and around the box, everyone was jumping on their seats on the bench. So yeah, we are so happy to have him, he’s going to help us so much, and now we have to keep him fit."
Asked if Havertz could start tonight, Arteta added: "We have to manage his minutes now, but he had a good block of 20-25 minutes the other day. He trained really well again today, it’s now a case of building his robustness and make sure that he’s available for every game."