I started working on a rewrite based on libclang targeting Qt5 a long time ago, but it proved to be a lot of work at the time, and later I had to abandon my projects altogether (work and kids are taking up way too much of time, I rarely have the time to follow up on lua-l anymore). There are other projects that may work with Qt5:
http://www.nongnu.org/libqtlua/ - works with Qt5, "just" a Lua scripting engine for Qt, not an automated binding and "not designed to develop an application in pure Lua"
https://github.com/torch/qtlua - it uses Qt4, but since it's manually written, it may be possible to easily port it to Qt5
