The Gunners were outclassed by Roberto Martinez's side at Goodison Park as they sit just a point ahead of the Merseyside club who are strongly challenging for a top four finish with a game in hand on the north Londoners.
"We've got plenty to play for still. We've got the FA Cup now, so we're going to have to switch on and focus very quickly and forget about this," he said.
"I hope we can kick on from now and start a good run.
"It's huge obviously. We know it's the only trophy we can win and it will be a massive boost for the club and the fans."
Steven Naismith and Romelu Lukaku scored in the first half for Everton before former Toffees midfielder Mikel Arteta conceded an own-goal just after the hour-mark as the Gunners saw their winless run extend to four in the league.
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