Hello,

As per your requirement, i would say that as mentioned above your query,for gate, skills or knowing multiple programming languages are needed. Only basic programming (particularly C) concepts required.
For placements, yes coding skills definitely help you. Knowledge and experience of different programming languages improves your chances. The companies may have specific requirements for some language skills thats where your experience with different languages may help. But its not necessary. You can have command on 1 or 2 only and that may be enough. What counts is how clear your concepts are.

Follow previous year papers and you will get the idea of questions and its pattern.

Good luck