Maximum number of electrons may be present in one 4f-orbital

For f subshell azimuthal quantum number (l =3). Therefore permissible value of magnetic quantum number(m) are +3,+2,+1,0,−1,−2,−3. This f subshells possess seven orientations in space i.e. f subshells contain seven orbitals. 

Max. no. of electrons in an orbital=2