Realistically, I don't think goal difference is a factor for City now. Arsenal are that bit ahead and also would need to have better results in the final games for it to come down to goal difference. So the chances of catching them that way are slim at best. Huge winning margins are usually pretty rare at the end of a season when all the games are must-win. Too much tension unless you score a couple really early.
It's going to be tight but you have to back this team to get the job done. If Arsenal lose to Spurs it's in the bag.
You would probably get incredible odds on us winning it on goal difference. But I think that ship has likely sailed.