It is indeed doubtful that Barcelona will be able to close the gap anytime soon. The only chance they have is to achieve an extended winning streak and then look forward to the second leg of the season when they play against Real Madrid at home in the Camp Nou stadium. It will be in the middle of May, which means by then the season will be mostly over. Then it will come down to whether or not by then Barcelona was able to catch up. If they have these inconsistent performances until then and Real Madrid stays solid, then I think there is no chance for Barcelona to have a say in this season's competition for the title.
Barcelona can't catch up with Real Madrid this season, they have already lost their chances of winning the league. They started the season very well but half way they lost the momentum and have not fallen from the to of the table that they were once dominating to the 3rd position. Barcelona has a chance to get back to the title race if they can keep winning their games, they're just 3 points behind Atlético Madrid that are in the 2nd position therefore the next fixture are very important to the two clubs as they need to win to either extend their lead for Atlético Madrid and close the gap for Barcelona. I think the both clubs are going to win their next fixtures.