Can't find anything definitive but I'm 99% sure that GPU functionality haven't gone live yet. BUt I came across this:
https://boxtail.deviantart.com/art/Clams-488829353which seems to imply there's a beta that has GPU functionality out there somewhere. Does anyone know where this is/if I could get a hold of it? I was going to purchase the full version but I'd like to do HD video renders and I'm not sure if the software will be what I need if I can't utilize my GPU... but if there is GPU, even just beta, access on purchase I'd do it in a hearbeat.