I think with Arsenal going 8 points clear at the top of the league table will increase the pressure on Manchester City to want to get a must win in their next premier league game. Manchester City are currently distracted with the champions league, they will be facing Dortmund in the UCL soon and I think Pep will prioritize winning the UCL over the epl because the champions league trophy has eluded him for so many years at Manchester City. He would not want to lose this chance. This gives Arsenal the advantage in the race for the trophy, Manchester city is not a team to underestimate so Arsenal will have to be at their best performances to win the title.
I think it's 8 points but since they have one more game than City, that means as long as City wins that extra game, the difference is still 5 points and nothing really changed aside from getting one more game closer to finish line.
Obviously Arsenal is still doing fine, there was this week or two where City looked like they might take over and ever since that moment Arsenal has been doing well enough with that 5 points difference and I do not think that they will give it away soon. There is this possibility that they could even keep this difference until the end, who knows? But that doesn't mean that it was this week that sealed the deal or anything, this wasn't anything special all by itself.