The match with Manchester City is a biggest one for Arsenal in rest of season as they are two direct competitors for the Premier League crown. Arteta and Arsenal don't have to win that match, they need to have a draw, prevent Manchester City to reduce 5 points gap and move on to collect points from other teams.
Don't think like that there are still 10 weeks to go, it's mean Manchester City can earn maximum of 30 points, it's enough to beat Arsenal at the top position. Arsenal always lost against Manchester City, so Arsenal still need to win regardless they're currently in a quite safe position and 8 points difference than Manchester City.
Maybe Arsenal have a slight advantage since Manchester City need to play at the other leagues, but it can put a pressure for Arsenal's players since Arteta will force them to win in this league, otherwise Arsenal will not get anything in this season.