From this Wikipedia page, I quote:
AAC products may be used for both interior and exterior construction, and may be painted or coated with a stucco or plaster compound
That would lead me to believe that the thermal expansion properties of AAC and plaster are similar enough that there wouldn't be any cause for concern about the coating flaking off due to cracking. Since a skim coat of plaster wouldn't be likely to crack off, I would assume that plasterboard/drywall would have similar enough properties to not be of concern.
Disclaimer: This is pure conjecture, but seems reasonable. I have no experience, professional or otherwise, to support this.
I would say, though, from further reading of that page, that it seems that AAC units are quite easy to work with, since they can be worked with standard woodworking tools, so you might want to consider filling in the voids with new AAC blocks instead. That would completely eliminate any concerns about dissimilar materials causing cracks.