Here I give a simple and complete example of how to develop Qt5 GUI with TensorFlow C++ library on Linux platform. Please check out my GitHub's repository as follow:
For building TensorFlow C++ APIs library, you can refer to my previous post:
I think the key point is how to prepare the CMakeLists.txt and you can refer to mine. If you use Qt Creator to open this project and make it, the GUI will look like this when running.
P.S: The related post for reference