I guess it goes both ways. One unexpected loss from City and the gap grows again. While City is always consistent in the 2nd half of the season in the last three years or so, they have different players now. It will be interesting to see if Pep can keep it up or switch his playstyle to be more pragmatic to win points in the remainder of the season.
Manchester City are very experienced in Premier League and they have many star players to alternate players in second half of season. It gives them more choices than their competitors and is important for them to play better than competitors and collect more points to take the title at the end. In the last six seasons, it happened in 5 seasons and the last season is an example. Arsenal hold the first position in most of season but in very last weeks, they lost it to Manchester City and ended it as a runner up.