No, an year drop, or even 2 year drop won't affect your placements. Companies least care about the time you took to clear the JEE. All they want is a knowledgeable candidate who can work efficiently for the organisation.

The companies realize that if a candidate is studying in an IIT or a NIT, he/she would definitely worked hard during his/her JEE time, which is the bottom-line for placement in any company or organisation.