If you have a strong grasp of Java. I fail to see why it would be hard for you to learn C# or even C++ for that matter.
Just go ahead and teach yourself already, its not some giant impossible to climb curve to learn the language of C++ or even C#. Only way you will do it is if you do it.
No language should be seen as a stepping stone to another language they are all unique in their own rights, claiming you know C# from Java is a ludicrous statement. They have several unique differences.