If the only thing he ever did was to prompt kids to check their answers, or to pronounce some difficult words it might rise to a level of a severe letter of reprimand. Firing is another issue, especially if it can’t be proven he actually gave away any real answers. It depends on the amount of “wink wink, nod nod, ahem ahems” he would use in checking those tests, in accodance with any interactions going on with studets in the “checking” process.
His school had some classrooms with wrong to right erasure rate at over 50 standard deviations from the norm. At seven standard deviations an event happens randomly less frequently than once in 390 billion occurrences. (I'm not talking 'statistics' very clearly).
He admitted he cheated. I'm almost sympathetic with him because he's one of the teachers who admitted cheating to the original investigators.