More than likely...
The adapters for digital backs that I have seen use the Graflok system to attach to the back of the LF camera.
My particular LF camera (Ebony) supports Graflok and I can turn the entire film holder back which inlcudes the Graflock mechanism to either landscape or portrait orientation. So, if I use any type of Gralok film holder, I can get portrait or landscape orientation with it.
You probably want to make sure that the digital back adapter can work in either landscape or portait. The specific adapter for adapting the digital back to Graflok, may not work in one of the orientations.
I know this may sound confusing, but if you see a system in action, its really clear and obvious.
FYI, Phase One backs that fit the Haselblad V system can be mounted in either portrait or landscape mode on the back of a hasselblad V, so for this kind of back being able to rotate the film back adapter on the LF camera may be less of an issue.
Hope this helps.
Rich
NGOphotographer