All the articles mentioning this figure come from low-key websites rather than top media outlets, so I tend to agree with those that doubt it and point out that it's just a rumour and/or a misunderstanding.
Now that you've mentioned it, this would've blow up already in Twitter and other crypto news website because 500B investment prospect isn't just any amount and it comes from an unlikely country so yeah I'm with you when it comes to the doubts regarding this news story, maybe there's more to this but I doubt that, this is the first time I've seen the opposite of FUD.