Rarebit (creators of Sass and Haml) recently published the 2015 results of their annual Ruby survey, now in its seventh year.
This year saw a significant shift to Ruby 2.2 (40%) following the shift to 2.1 last year (50%). Only about 15% of rubyists remain with Ruby 2.0 or below. JRuby adoption remains below 5%.
For production the preferred web server remains Unicorn (40%) over Passenger (30%) though Puma adoption has reached 15% in its first year now that Rails 4 has better concurrency support.
If you are a full time Ruby developer I encourage you to participate at http://www.askr.me/ruby