Hi Niteesh, 

One year gap would not be a big problem till you will be able to justfy it ta the time of interview. But instead of taking gap you can join any organisation for a year and at the same time start prepring for CAT. One year of preperation is enough to get a good score. In this case it would not be considered as a gap year. During last 3 months from CAT exam you can leave the job and can start preparing full time. It will make it easy for you to justify in interview. 

Its upto you, both the options are good and won't make much of difference.

All the Best