Deadline has released details behind a major deal between Netflix and Warner Bros. In a deal the first of its kind, Netflix has purchased rights to be the video on demand service for Gotham not just in the US, but everywhere the service extends internationally as well.
This does not change anything as far as the series airing on Fox, it just means that Netflix will have the first season of the show most likely prior to the second season to be able to be viewed by subscribers of the service.