If Barcelona wants to win the title this season, they have to be able to beat Girona in this week's match, I know it may be difficult for Barcelona but it seems like there is no other way to catch up, they can steal full points in the match later even if they only win At least Barcelona can keep the points gap with Girona from being too far away and can get rid of Girona and then Madrid.
It is not true as the title will be given to the champion at the season ending, not now, not after the match between Barcelona and Girona. Winning or failing in this match will not decide Barcelona will successfully defend their La Liga title or lose it to Girona or Real Madrid or other clubs. There are many matches in rest of season that will be more decisive for the league title.Quote
I know that Girona has played very consistently so far but sometimes they never manage to face the strongest teams in Laliga like Madrid and Barcelona, playing away from home it will certainly be difficult to beat Barcelona, I think they will probably play as hard as possible to not lose points, my prediction the result will be a draw or Barcelona will win narrowly 2 - 1 
In a season, a team win a league title even don't need to beat all big clubs. They have to do a more important task, collecting as many points as possible from all matches in the season. Winning direct competitors is good but not enough to win a title because total points come from all matches in the season with all opponents at home and home-away stadiums.