Cineuropa mentions the possibility of the film potentially being part of the film festivals:
The Uma Thurman and Robert Pattinson vehicle Bel Ami, adapted from Guy de Maupassant’s short story, will be ready for Cannes or Venice. Rights have already been sold to Studio Canal Plus for France and Germany. Optimum has UK rights.
LeRPattzClub tells us the lineup for Cannes will be unveiled in April, while we won't know what films will participate in the Venice film festival until July. It seems we don't have much choice but to wait and see!