Fulham did humiliate both Nottingham Forrest and West Ham by scoring 5 goals without conceded, yet they're struggle when they face top clubs. Crystal Palace is nothing different with them, a weak club, so I don't expect Arsenal will join the title race just by winning with big scores against weak club.
Although Arsenal has an advantage in terms of players availability than Liverpool...
Every match in the Premier League is a big game because you are not sure of taking the whole three points until you have played your match and won. Arsenal is already in the Premier League title race because they are in the third position in the Premier League table, with 43 points and two points behind the Premier League table leader.
Each team certainly has its own problems, including Arsenal who had experienced a decline in performance. So it could be that this obstacle will also be felt by Liverpool or Man City in the future and at the same time Arsenal will find their best performance again. The big win that Arsenal got against Crystal Palace keeps making their chance in the Premier League title race because this victory could be their comeback or it could be the beginning of the return to their best performance.