If a spell is defied or otherwise countered, does that original card still count as being "played"? For example, would Blue Viktor be able to play his token?

No, a card that is countered is not considered to have been played.

According to Rule 412.1.b: "A card that is Countered is not considered to have been played."

Because the card never finishes the process of being played, it will not trigger "When you play..." abilities. In your example with Viktor, Innovator, if you attempt to play a card on your opponent's turn and it is Defied, Viktor's ability will not trigger, and you will not get the Recruit token.

This is further supported by official rulings:

• FAQ Ruling: "A card that is countered is not considered to have been played, so it does not count for effects that check 'if you played two cards this turn' or similar conditions."
• FAQ Ruling (Viktor specific): "'Play a spell' triggers require the spell to fully resolve, so Viktor Inventor [Innovator] will not trigger if the spell is countered."