An additional Champions Cup will grant the winner a spot in the Spring Major Regional Qualifiers.
With the release of the Fall 2016 Battle Pass (more info on that here) a new season for Battle Cup was announced with one more bonus for the best players. They will be invited to an end-of-season Champions Cup and the Tier-8 winners of that will be eligible to form a team with other tier-8 winners to compete in one of four Spring Major Battle Cup Qualifiers. Win that with your formed team and you get a spot in the Spring Major Regional Qualifiers.
This will be alongside everything established so far, there will still be open qualifiers, there will still be invited teams, provided they didn’t break the roster lock and performed well enough. Now one of the Open Qualifier slots will go to the people, who best all their peers in the Battle Cup and formed a new team. This will go for all four regions, with one Battle Cup team per region.
Battle Cup winners will get similar rewards to last season – battle pass levels a, trophy, champion status for one week and a streak counter to show off how many cups you got in a row. In addition to that every player on the winning team will get two treasures. Battle Cup achievements are added to the Battle Pass, unlocked in a similar manner to all other achievements and a convenient way for you to track your progress.
If you need a refresher on what Battle Cup is and how to participate, info is can be found here.
Source: Dota 2 Blog, Battle Cup FAQ