Bayern Munic is still in the champions league whereas Bayern Leverkusen is not, this means that Leverkusen have more time and energy to focus on the league alone. You will recur that because of champions league match, both of them lost two weeks ago, this should tell you how much the champions league can affect clubs. So, Bayer Leverkusen still have a chance of closing in on Bayern Munic and even snatching the league from them. They simply need to continue winning their matches and avoid playing draw as much as they can because they don't need draw now.
Bayer Leverkusen don't seem to be as hot as they were in the last season when they won the Germans bundesliga with an unbeaten record. This season they have dropped in form which is very obvious with the results they have been getting on this season and how they've struggled to win certain games and their elimination from the UCL says so much about their drawbacks.
Though they have been on the tail of Bayern Munich in the domestic league so far but Bayern on one hand has made sure to maintain their lead despite their engagements in the UCL which actually isn't anything new for them and with the depth of their squad they can continue winning their games in the bundesliga and still have a good run in the UCL without Leverkusen catch-up on them.