If you create a token that's a copy of Eloise and both are legendary, you will choose either the token or the original Eloise to keep and put the other into the graveyard. This is not the same as sacrificing it. Putting the token into the graveyard won't cause nontoken Eloise's last ability to trigger.

If you sacrifice a Clue token, Eloise's last ability will trigger in response. You'll surveil before drawing the card.

Eloise's last ability triggers whenever you sacrifice any token for any reason, not just whenever you sacrifice Clue tokens.