The Ghana international has not played since suffering a groin injury in training in early September.
"He’s been progressing really well in the last two weeks, and he managed to train the last two or three days with the team. That’s great news for us, obviously," Arteta said on the team's official website on Monday.
"He’s progressing and has been very good in the past week. He is a big player, and we know what he brings to the team."
Arteta also gave an update on Bukayo Saka's condition after the England International had to come off during Arsenal's 4-0 victory at Bournemouth in the Premier League on Saturday.
"Obviously he took a big knock but he’s recovered well and he trained today," Arteta said, adding that a decision about Saka playing would be made on Tuesday.
Arteta emphasised that Arsenal would not underestimate Lens, even though the Ligue 1 runners-up from last season have had a disappointing start, currently sitting in 15th place.
"This season they have been really unlucky with some results. I don’t know how they don’t have more points, so we expect a huge battle tomorrow," he said.
Arsenal's travel plans were affected by severe storms in southern England, resulting in a nearly five-hour delay to their flight to France, British media reported.
Arsenal top Group B after a 4-0 home win over PSV Eindhoven on matchday one, while Sevilla and Lens drew 1-1 in Spain.
