There's been some discussions regarding this topic. Here's a thread with some contradictory answers:
Does the views in the embed player count?
And here's an article about an official response from Youtube claiming that autoplay views does not count:
Youtube Says Autoplay Don't Count
Here's another one that claims that embedded videos with autoplay doesn't count:
How does YouTube video view count work?
(found through this SO answer)
Note 1: Note that there seems to exist "cheats" and bugs, but Youtube claims to be working to prevent it. This means that, if you're using their API in a regular way, your autoplay views probably doesn't count.
Note 2: The above note is simply Youtube's official statement. Who knows what's really going on. Some people (including you, OP) are getting mixed results.
The bottom line is, don't count on it (pun intended).
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