Maybe Arsenal will benefit a little because Manchester City must share their concentration on the Champions League and also the FA Cup. But I'm sure Arsenal will lose points again when they face Manchester City. So in my opinion Arteta has to maintain that two-point gap that is very likely to happen. This means that if you want to keep the chances of winning, Arteta must not let his guard down in every remaining match.
I don't think it will affect Manchester City's concentration during the game in the FA Cup, because they have a reserve squad depth that is balanced with the main players, but in the Champions League I think it will affect Pep Guardiola's concentration, because they will face Bayern Munich who have a balanced game with them.
Meanwhile, Arsenal have to undergo two big matches in the Premier League and are quite worried because the matches against Manchester City and Liverpool will be the toughest test for Arteta. If Arsenal lose concentration and fail to secure full points, then the potential to maintain the top of the standings is in danger of being taken over by Manchester City.