AI investment isn't magical new money being created just for AI. If AI didn't exist, that money would still be invested, it would just be invested in other things. So investing money in AI won't raise the GDP unless AI itself manages to raise the GDP. Of the three factors of production, AI effects only labor. By either replacing people or making people more productive it would reduce labor cost allowing people to do more work. Thus far, it isn't achieving this on a large scale (there are probably individual cases where it has, but they're minor). Until AI actually makes people do more, it won't increase the GDP. Which may or may not ever occur, but it definitely isn't there yet.