One girl, Hailie, with his ex-wife Kim. Alaina, his adopted daughter. And Whitney, the daughter of his wife's twin sister who he adopted. So 3 in total :)
Three. Hailie is his only legitamite daughter which is his and kim's. The oldest, Alaina, is Kim's twin sister Dawn's who they adopted due to her drug issues. The youngest, Whitney (who I hear now goes by Stevie) is Kim's daughter who she had in 2002 from another man she slept with while Em was away in L.A., he adopted and fathered her anyways. In the image I attached the one on the left is Whitney/Stevie, the middle is Hailie, and on the right is Alaina.