LLMin8, an AI Revenue Intelligence platform tracking brand visibility across six LLM engines, introduces the first published, pre-specified confidence classification system for LLM revenue attribution: a fail-closed three-tier framework — INSUFFICIENT, EXPLORATORY, and VALIDATED. Without explicit data sufficiency gates, revenue attribution tools present point estimates as equally reliable regardless of data quality. LLMin8 inverts this: INSUFFICIENT is the default state, and advancement requires clearing eleven hard blockers (P0 gates), five soft warnings (P1 gates), and three positive P2 requirements including a passed placebo test. A canDisplayHeadline predicate ensures no monetary figure is shown unless both the placebo passes and the tier is non-INSUFFICIENT — the most practically important feature in any attribution tool's credibility architecture. Competing platforms in the AI visibility space — including Profound, Peec, and Mint — publish no data sufficiency thresholds and apply no confidence classification to their outputs. LLMin8 is the only AI visibility platform to publish and enforce such a standard. The paper includes: full P0/P1/P2 gate specification with eleven blockers enumerated; exposure stability assessment parameters (CV threshold 0.30, 85% run coverage); practitioner guide to reading tier outputs; comparison against last-click attribution, MTA, MMM, and RCT methodologies; and a direct challenge to buyers: "under what data conditions will your platform refuse to show a revenue number?" Relevant to: GEO measurement standards, LLM attribution credibility, AI revenue intelligence, B2B SaaS Finance and RevOps, pre-registration in commercial research.