Yes.  I can't think of a better match as an accessory.  In fact, I consider the combination to be a SuperH9.  Because the 8 Step output is expression pedal-based, the only limit is your imagination (controlling the H9, or any other hardware with EXP PED input).  And because the 8 Step input is MIDI-based, you can control, adjust, sync, etc. with the rest of your system.  Tight integration.

Remember to set the Depth to 5 for Eventide pedals. I run an expression pedal 'through' the 8 Step, for foot-controlled or automated options at the same time.  Any setup is extremely easy now using the H9 Control app.   [NOTE:  Don't try to program your expression pedal settings while the 8 Step is running in Play mode!].  I can't begin to detail all of the control options that you have on the 8 Step end.

Just read over the manual for each type of operation (Glide, Direction, Sequence Length, Rate, etc.).  After a few run-throughs, it'll all become second-nature.  You can probably start with most any H9 factory preset, and see how it reacts under 8 Step control.  Multiple parameters locked to the expression pedal is like morphing among several presets at a time.