Instant Articles - embedding a tweet
Just Try in a simple way,
1) Copy the URL of tweet.
2) Paste the tweet URL on a line in your article/page (as a plain text)Note : A Tweet link must look like a line, it must be Unlinked.
3) Now Publish it, your tweet will get embedded on your article/page.If it doesn't work for you, Just edit the page and Unlink the Tweet URL.