Honestly, I don't think it's possible for Arsenal to catch up with Liverpool, as they are in great form at this point. Fifteen points is not a small gap, and again, there are only a few matches remaining for the Premier League season to end. I don't know how it could happen for Liverpool to lose all fifteen points with only nine matches left for them. During the period when Arsenal had a great opportunity to close the gap with Liverpool, they were messing up. At that time, the points difference was just 7 points. If Arsenal had won those matches, the points difference would have been just 3, and they could have seriously hoped for winning the Premier League. But I don't think Arsenal have any hope left for this season in the Premier League.
Even though Arsenal aren't playing in any other competition except the Premier League, and Liverpool is still in the Champions League and other competitions, Arsenal still can't win the Premier League at this point. We have been watching Arsenal for over three seasons now, and with the kind of opportunities they always have, they still mess it up. In the last three seasons, Arsenal were out of other competitions to focus on the Premier League, but still messed up.
Liverpool are currently eliminated from the Champions League competition, and with their elimination from the Champions League, the EPL will really be their main focus this season, so that at least this season they can present one trophy to their fans. And seeing the fairly large points difference that Liverpool currently has, it seems impossible that there will be a team that can match Liverpool's points, even though Arsenal is currently in second place in the standings.
Likewise, because Arsenal is no longer able to seize the top position from Liverpool, and because Arsenal is one of the teams still competing in the Champions League, I hope that apart from Arsenal, they can maintain their position as EPL runner-up until the end of the season. However, I also hope that they can get the best results in the Champions League, because until now Arsenal is one of the teams that has never won the Champions League title.