Plasmonic waveguides exhibit an effective epsilon-near-zero (ENZ) response at their cut-off frequency. In this work, we demonstrate a nanoscale parity-time (PT) symmetric nanophotonic device based on gain medium embedded inside the nanochannel of a plasmonic waveguide. The effect of introducing gain is more than loss compensation and can cause a plethora of new interesting phenomena. In particular, the interplay between loss and gain will lead to super scattering at the exceptional point obtained close to the ENZ resonance frequency. This interesting effect is made possible by introducing an active material with small gain coefficient inside the plasmonic waveguide. When the proposed active waveguide is illuminated by two counter-propagating plane waves, the output ENZ power becomes unidirectional. In addition, the ENZ response can be dynamically modulated from strong scattering to perfect absorption just by changing the phase difference between the two incident waves. Strong fields are obtained in the nanochannel of the proposed PT-symmetric plasmonic waveguide, which are found to drastically boost optical nonlinearities, leading to strong optical bistability and switching at the ENZ resonance.