Hello candidate,

Thank you for contacting careers360. A gap between 10th and 12th does not matter for admission in IITs. And if you're getting into a good college, no one would ask you the reason for the gap.
According to the rule you can give JEE the same year you completed your 12th and a year after that. So, in short you get two chances to get admitted into IIT. I would suggest you to not to take a gap after 12th because you'll be left with only one chance after that.

Best of luck.