I am looking into using Pixate with iOS 7/8 app.
I use AutoLayout extensively so I want to make sure it works.
The parts of Pixate Freestyle that specify style do not conflict with Auto Layout. Some lesser known pieces of Pixate let you specify positioning and such, and I suspect that Auto Layout constraints will override what's in your Pixate CSS.
But if you're just using Pixate for style, you're good. I styled an entire Auto Layout app with no problems.