I doubt the Ruby ecosystem is the largest out here. In terms of packages, npm more than 1 million, Maven Central (Java) 438k, PyPi (Python) 336k, Packagist (PHP) 323k, NuGet (C#) 260k, CPAN (Perl) 202k, Ruby has 170k gems, Rust 70k, Elixir 16k, Haskell 16k OCaml 3445. I couldn't find information for Go, and nothing specific for Scala and Clojure. Out of those the most comparable are Java, Python, PHP and C# due to the existance of Spring, Python, Laravel and ASP.NET competing against Rails. All of them have a bigger ecosystem compared to Ruby. In terms of scripting languages, Perl, Python and JS all have bigger ecosystems.
Of course you could reply about the quality of packages, but first, that's moving the goalposts, and second, why would the Ruby ecosystem be any better?