QtQuick already has a lot of useful stuff built in: a scene graph (behind the scenes), shader effects, vector shapes, text, ... (and widgets of course). I'm not really sure what you're hoping to get by "integrating" SFML to it.
And even if something's missing from QtQuick, I'd already search within the variety of libraries built for it, rather than trying to port something that is clearly not made for it. For example, you can have a look at V-Play, which is a fully featured game framework built on top of QtQuick and QML.