While it would undoubtedly be cool if this was a thing, it isn't.
Thunderstrike says (PHB p.62)
At 6th level, when you deal lightning damage to a Large
or smaller creature, you can also push it up to 10 feet
away from you.
So far , so hoopy.
Space says (PHB p.191)
A creature's space is the area in feet that it effectively
controls in combat, not an expression of its physical
dimensions. A typical Medium creature isn't 5 feet
wide, for example, but it does control a space that
wide. If a Medium hobgoblin stands in a 5-foot-wide
doorway, other creatures can’t get through unless the
hobgoblin lets them.
So, there is plenty of room in a creature's space for them to duck, jump or otherwise dodge out of the way of transient thunderstrike victims.
Now, in D&D 5e, things do what they say they do and no more; there is nothing that I can find that says a creature moving through another creature's space has any affect on that creature.
TL;DR
He moves through and past the other creature with no other effect.