It is unlikely that the Brewers would win a tiebreaker against the Braves even in the highly unlikely event that the teams end in a tie. And yes I am intentionally stacking unlikely on top of unlikely.
For the teams to end up tied the Brewers would have to blow a 5,5 game lead in 11 games. That would require the “wrong” result in exactly 16 of 21 games. That would be a collapse similar to the 1964 Phillies who lost 10 games in a row to blow a 6 game lead with 12 games left. But 3 of those games were head to head against the Cardinals, who ended up winning the pennant, making the possibility of making up the deficit a little less improbable.
For the Brewers and Braves to end up tied, the Brewers would have to lose exactly 6 more games than the Braves the rest of the way. That would mean the Braves going 10-0 to the Brewers 5-6 or the Brewers going 0-11 to the Braves 6-5, or some point in between. But, in any event, those 6 extra losses would probably flip the tiebreakers which are currently close in the Braves favor.
For the Brewers to win a tiebreaker their losses would have to fall just right. For example, in the Braves going 11-0 scenario, if the Brewers won the 5 games against the Pirates and Cardinals and lost the other 6, the Brewers would win the division tiebreaker at 36-16 to the Braves 35-17. But if just one of the losses were to come against one of the Central teams, the Brewers would lose the intraleague tiebreaker.
So, I’m just going to ignore the tiebreaker and count down the magic number from 6 to 0. The odds of the Brewers winning a tiebreaker over the Braves may not be astronomical, but they are several times larger than the probability of the Brewers losing the division were 10 days ago.