No, sorry. For my understanding - and this is in agreement with most of all relevant textbooks - a low pass has a usable bandwidth which equals the cut-off frequency.
Concerning Q: The cut-off frequency as well as the filter shape (low pass approximation) depend, of course, on the inductor Q (and the source impedance).
It is really simple to calculate the transfer function and to verify that each part determins the frequency behaviour and the cut-off frequency - even a parasitic resistance of the lossy inductor.