Arsenal did not show their potentiality to play better, perform more consistently to catch Liverpool. It's their main first target to achieve but with their inconsistency, it's nearly impossible. Their competitor Liverpool, like you said, are simply stronger and more stable, so they will continue playing well and not only maintain 8 point difference with Arsenal but also wait for chances to expand it bigger and bigger.
The season is counting down very last matches till the end, and each good match with three points will bring Liverpool nearer to Premier League trophy. Arsenal with each bad match will give Liverpool extra help to win the title earlier than the final match day of season.
You can't talk about their potential because Arsenal with Arteta have never become champions, and the second step in the championship is their limit, so I think that we can talk about potential if they were lower than this position, and if they are second after Liverpool, then this is their usual level, which they are capable of. Liverpool gave them a chance to get closer several times, but they did not use them, and the difference is now 11 points.