Barcelona doesn't have to win by a landslide, they just need to win every game even with a narrow score, that will make them comfortable in their current position. Barcelona managed to take advantage of Real Madrid's decline, so they have an 8 point advantage now. Things like this are what they have to take advantage of, yes they have to take advantage of any results that are not optimal from their eternal competitors.
This is the only thing Barcelona needs to do that might not be easy for them. Winning all their remaining games is a guarantee for them to win laliga this season. Making mistake to lose any game will be opportunity for real madrid to stop Barcelona from winning the league.