Just for clarification, can Whisper use the gained evade token when the attack hits to use Juke on the Opponent???

No. The attack is not determined to have hit until well after the opportunity to use Juke has passed.

Whisper gains the token after the attack hits.
An attack hits at the End of step 4 if at least one [hit] or [crit] result remains uncanceled; otherwise, the attack misses.

Therefore the next step is 5 where Whisper cannot use her ability.

For reference...

Sorry to pile on, but we've covered Whisper's extra evade timing really well without mentioning Juke's timing at all, which could very well be a source of confusion.

Juke is a dice modification. Dice modifications happen at a specific time (basically, immediately after the dice are rolled). So an attack with juke Whisper looks like this:

1) Declare target / measure range / pay costs etc

2) Attacker rolls attack dice

a) Defender mods attack dice

b) Attacker mods attack dice

3) Defender rolls defense dice

a) Attacker mods defense dice <-------- [JUKE HAPPENS HERE]

b) Defender mods defense dice

4) Neutralize results

a) Evades cancel hits

b) Evades cancel crits

c) Determine hit/miss <--------- [WHISPER ABILITY HAPPENS HERE]

5) Damage