Unless there was deliberate action (skipping procedure in a way that a person has been warned and disciplined about previously) there will be no firing.

Any calculation based on the hours down needs to be reduced to account for people finding products by other means (already saved for later in their basket, direct links, searches via external search engines).

This is so inaccurate. There is no way that the distribution of product sales is constant over time of day, day of the week, month of the year, etc.

I highly doubt search equates to all of their sales during a period. That would seem odd and would indicate no one uses their navigation at all.

Firing seems like a toxic move, especially without knowing what happened. I'd like to think that Amazon has multiple layers of alerts built into place for situations like this, so this was probably a complex bug (perhaps a perfect storm of faulty configurations like what happened with Google's Cloud offering not too long ago).

I'd say that number is probably a ceiling on their losses, and that the actual number should be much lower. I'm super curious if non-tech news organizations will pick up this story, in which case the biggest hit could be from the PR. That being said, it doesn't seem like such a bad time to go down.