According to Variety, theater actor Ray Fisher has been cast as Cyborg. Further implying that this film is seemingly turning into a Justice League movie more than a Superman/Batman film. (And that was speculation since nothing has been confirmed if this sequel is indeed a full blown Justice League movie.)
However, no details were provided so Cyborg (a.k.a. Vic Stone) may just be quickly introduced. Man of Steel did have an Easter Egg for S.T.A.R. Labs which is where Cyborg's origin story begins.
Stay tuned because Batman vs. Superman, or whatever you're calling the Man of Steel sequel, just became even more intriguing. Filming in just about ready to get underway in Michigan Motion Picture Studios near Detroit.
And here's what Fisher looks like (image via Variety).