Is there a Quantum equivalent of the Time hierarchy theorem ?
The answer is no. We don't even have a time hierarchy theorem for bounded-error probabilistic polynomial time (i.e., BPTIME).  The deterministic and non-deterministic time hierarchy theorems have a diagonalization argument, which does not seem to work for semantic classes. This is why we don't have strong hierarchy theorems for semantic classes.

The best result I'm aware of is a hierarchy theorem for BPTIME with 1 bit of advice: Fortnow, L.; Santhanam, R. (2004). Hierarchy Theorems for Probabilistic Polynomial Time.

I don't know of any groups working on a quantum time hierarchy theorem. I would guess that this is because it seems like the BPTIME hierarchy problem is easier, so researchers would attack that problem instead.

(Somewhat related questions: Is there a syntactic characterization for BPP, BQP, or QMA? on MathOverflow and Semantic vs. Syntactic Complexity Classes on cstheory.)