You know a week is avery short time. I hardly believe you can properly prepare yourself for the interview. However:
C++
has a new standard. If you have already a good knowledge of the language I suggest you to learn just a few highlights, this article, in my opinion, is good for:
Ten C++11 Features Every C++ Developer Should Use[
^]. On the other hand if you don't know
C++
, you better try to understand the basics of the language.
I don't know
QT
so I can't suggest you anything on this argument.
If you already know
SQL
, then I suppose a quick refresh of your knowledge would suffice.
On the other hand, if you haven't a working experience with, it is time of studying an make a bit of practice.