Cusack has stepped up this season in the absence of Pocock, who has missed eight games through concussion and a niggling calf injury.
Wallabies star Pocock is not expected to return to Super Rugby after the World Cup in October, with the Brumbies also interested in signing NSW flanker Will Miller.
Cusack played rugby sevens at the 2016 Rio Olympics and the 26-year-old wants to represent Australia again at the Tokyo 2020 Games.
His new contract will allow him to play sevens in the Super Rugby off-season.
The Short Ball discusses draws in Super Rugby:
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