I am pretty fluent in ruby, which I learned after PHP specifically because I wanted to migrate, and I really enjoy using it. However, compared to PHP ruby is slow, it took ages before it had a half-decent unicode solution, and once you step out of the rails rah-rah it's a bit desolate on quality libraries... there's 10 half-built versions of everything, and no decent go-to implementation. On the plus side, ruby is nominally better for reflective metaprogramming, but that's really a rare use case.
The "fast PHP7 engine" part not. Raw Ruby was slower (but comparable) to raw PHP, so with this new engine which consistently runs real life workloads 2x, PHP7 should be like twice as fast.
And PHP still has more vendors, support in all kinds of hosts, even in third world facilities, and more companies offering commercial support. Plus there's stuff in PHP that don't exist with the same level of maturity/adoption/community in Ruby/Rails, e.g. Wordpress.
It may be, but the above poster also left out one of PHP's strengths - availability. It's already running and ready to go on whatever cheap shared host you've been on for the last 20yrs. Ruby/Rails likely isn't.