Midfielder Merino has been filling in up front in recent weeks because the Gunners have been hit by injuries in attack.
The Spaniard has started the last six games for Arsenal and has excelled during that run.
“I think he \[Merino\] has earned, at least, the thinking behind it for the way he’s performing and the impact that he’s bringing to the team, so that’s a yes,” said Arteta.
Unai Emery’s Villa have been in fine form of late and climbed to third in the Premier League table in midweek after beating Brighton 4-3.
“For what they’ve been doing, the way they’ve been playing and winning matches, certainly it’s a team that is in great form and we know that,” said Arteta.
“We know obviously the manager and the incredible job he’s done there as well, so we know the task tomorrow but we always take it as an opportunity.
“Every time you win a game, obviously you are a little bit closer to your objective and it’s the only thing that we can do.
“We have to focus on performing, preparing really well for tomorrow, we know the kind of game that we're going to play and be ready for it to fulfil our potential.”
Asked if predecessor Emery would be extra motivated against his former club, Arteta said: “I don't know. I think when you look at Unai, his career, his motivation level, everywhere he’s had an impact, it's all been remarkable.
“So I don't know, that's a question for him. But in my opinion, he never needs anything extra. I think he's good enough in himself.”