No, Marty, I really did mean short vowel in last (unstressed) syllable. To be accurate, it's not really pronounced as short 'i'; being in the unstressed final syllable, it's actually pronouced more like schwa.

Sez hu? NZ standard pronunciation is definitely "fortnite", and I have never yet heard anyone pronounce the word in the manner you describe. The pronunciation you describe screams "Sloane Ranger" to me, or perhaps the sort of person who still thinks "u" and "non-u"