Not only did they not fire him, they promoted him He was Senior VP of Microsoft Interactive Entertainment (which was basically just Xbox at the time) when he made that insane statement about selling between 400m and 1 billion Xbox One units and 15 million more Xbox 360 units. 2 years later, they promoted him to Corporate Vice President of the Windows and Devices group (which included Windows 10, Surface, Bing, MSN, Skype, and Xbox). He actually had a pretty good stint as CVP of Windows and Devices group though, in his final year as head of the group, the group pulled in nearly $40b in revenue and over $8b in profit. He is currently head of the Modern Life, Search, and Devices group, which is in charge of all of the same stuff as his earlier role, minus Xbox, which is now in it's own division under Phil Spencer.
He most likely follow that american phylosophy of dream and talk big =] (but yes I wouldn't expect this from very conservative Japan).
And now out of the joke, as you said besides making a very wrong prediction (that well he isn't responsible to achieve alone) his actions on the department improved their bottomline so most likely the promotion was deserved.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"