Hi,
thanks for your interest in Cubasis! In general of course any MIDI keyboard would work through a compatible audio interface and MIDI IN input. As for direct USB connections, the Launchkey 49 is listed as USB class-compliant, so in general it should be supported. If found this other topic somebody using a keyboard from this series, but most of the external controllers transport functions are not supported:
Please feel free to ask more questions…
Thanks
RG