After B.Tech in computer science, can I get a job online that I can do from home?

Sure, there are lots of jobs that require work from home interns for their company. For getting an idea on work from home jobs, you can consider working as part time intern while you are pursuing your B.Tech. Make the best of your time and you'll able to find your desired field of work.

A lot of jobs you can get and it will depend on your strong domain and your interesting domain.