Since the loanword came from French the earliest English usage was definitely 'neesh' and therefore the 'English' word thus created used that pronunciation. Of course, if you're referring to the much later bastardised American mangling of the word

Not sure what English pronunciation you're typing of. The OED, first edition, allows only /nItS/. The American-Heritage gives both /nItS/ and /niS/.


Ceci n'est pas un seing.