It actually doesn't. The Texans can lose this week and the Bengals, Browns and Colts can all make it ahead of the 11-7 Bills.
A Browns loss this week means that either the Browns or Bengals will be eliminated from reaching 11-7 when they play each other.
And because the Colts play the Texans later, one of them will be eliminated from reaching 11-7.
So a Texans victory over the Browns means that only two of the four teams: Browns, Bengals, Colt and Texans can reach 11-7.
So if only the Browns lose this week, the Bills control their own destiny.