Depends on the reason. Have an explanation and support evidence. A friend just went through it - he had some family issues to address. Also have a story straight
I had 95 days of unemployment on F1 OPT before I started my job (only 90 days allowed). My interview is next month. Will that be a problem?
Generally is not, but the officer is likely to ask you though. Be ready with a valid explanation backed by documents.
Few months should be no problems, a year might be, and I that vase your h1b may not valid for that gap