You don't tax automation directly, that would be a stupidly Luddite idea. It might create jobs, but it would definitely reduce efficiency and economy growth, which with a UBI, you want. It would also probably be a bureaucratic nightmare to enforce.
But yeah, figuring out how to craft taxes to make this work would be tricky. As I've said before, I do think that we're not at the point where we could make a UBI work yet.