can Thrawn give tokens to figures Lying in Ambush ?

A group with Lying in Ambush attached are out of play (and also its figures are not deployed), so no, i.e. I don't think you can.

In case anyone is curious about this question " Thrawns' (skirmish) Long-Laid Plans ability: how many different power tokens can he distribute at the start of his activation in the 5th round? 4 or 5? (if 5, then 2 of the tokens will not be different.)" This is the official reply from Todd: "In rounds 5+, Thrawn can only distribute 4 tokens, as they MUST be different."