If the startup fails, how do I explain the gap to future employers?

Stop calling it a gap, it's a founder role, and you frame it exactly like any other job: what you built, what you learned, what you owned end-to-end. Good employers read 'I started a company that didn't work' as evidence of initiative, resourcefulness, and real ownership, not as a red flag; the ones who penalize it are telling you they're not worth working for. Keep a crisp two-minute story about the bet, the outcome, and the lessons, and most interviewers will lean in rather than flinch.