Oh good lord, I am so sorry I missed replying to this for so long. Thank you for your patience!
This is actually a point that I’ve been thinking about for quite a while. In the original galileoace document, IIRC, “ga’I” is considered superfluous most of the time. I’m not sure if @tinsnip and I ever came to a conclusion one way or another in our expanded language, but personally, I suspect “Nu sUtis ga’I” would be formal/classroom Kardasi, and “Nu sUtis” would be more common in everyday use.
There may also be regional variations as to whether “ga’I” is considered necessary or not, but while I’ve been musing over Kardasi dialects for a good long while, I’ve not sat down and really solidified anything.
So, tl;dr: As of right now, both work, depending on who’s saying it!