Yes. The cells can be sorted into 1X Cell Lysis Buffer, flash frozen and stored at -80°C. If, instead, the cells are collected in PBS or water before freezing, make the 1X Cell Lysis Buffer according to Section 1.2 (Cell Collection and Lysis) of the manuals supplied with the NEBNext Single Cell/Low Input RNA Library Prep Kit (NEB #E6420) or the NEBNext Single Cell/Low Input cDNA Synthesis & Amplification Module (NEB #E6421), taking account of the volume the cells are stored in.