As Lori states, DTI for Office 2013 is not supported with 10.1, however we do seem to be able to use it without issues so far with 10.1 M040. How much longer I will be saying that remains to be seen.
As Microsoft pedal their O365 licence in the cloud model, it means more and more people will be constantly using the very latest version of Office. If PTC continue to be months and years behind in terms of DTI support this potentially poses a problem. I would be interested to hear PTC's view on this issue.