I have done my Diploma in IT after 10th. Am I eligible to study BCA? Would it be valuable to apply for services sector?

Yes, you can do BCA as well as B.Sc after Diploma in IT. They will give you services too but why BCA. You are eligible for direct admission to B.Tech 2nd year provided that you have scored at least 60% in final year Diploma. Coming to your question, you can't directly take admission in 2nd year BCA.