The first paid DLC of Battlefield 1, 'They Shall Not Pass" is apparently being teased. The official Twitter account of Battlefield posted an artwork, in which you can see an intense bunker shoot-out with French flags hanging from the walls. The picture is captioned "Soyez prêts", which translates to "Be ready". And since it has been confirmed before that 'They Shall Not Pass' will introduce French army to the game, it is extremely likely that this artwork is teasing the DLC.
You can see the picture below:
They Shall Not Pass is scheduled to release in March, 2017. It can be accessed via the $50 season pass of Battlefield 1, this way you'll also get your hands on the content 2 weeks before anyone else does.