A YouTube "partner" is an actual term in YouTube that basically means you have a special broadcaster account that shares ad revenue with you. Basically, she makes popular YouTube videos.
I think the question is about "creator". I'd take it as 'I created youtube' but maybe it's just me not being a native english speaker.
Native speaker here, and "YouTube partner and creator" definitely comes across as "I created YouTube and sit on the board of directors". Unless of course you know that YouTube has a user type called "partner", which is not common knowledge. Without a doubt, some of her followers are under the impression that she created YouTube if they didn't do any other research about it.
However, these are two different situations. It's different when she is a public face of SendGrid and her Twitter profile states "Developer Evangelist for @SendGrid". I'm not saying that this post merits her being fired for anything. I'm just saying that, in such a position, her twitter posts should not be immune from judgement and action by her company.
Edit: Off track but her Twitter profile also states "YouTube partner and creator" .. what?