Assuming that the first flight is booked under the AS flight number, then this is actually a question for Alaska Airlines, not Cathay.
From:
http://www.cathaypacific.com/cx/en_H...-baggage-rules
All the below rules apply to the whole of North America, including the U.S. and Canada.
1. If your journey is to, from, or has the furthest checked point in the U.S. or Canada, you may use the rules of the first marketing carrier on the journey, provided that the first marketing carrier is specified on ATPCO’s (Airline Tariff Publishing Company) published lists of US DOT and CTA carriers. These are defined as carriers where general rules tariffs to/from the U.S. or Canada have been filed.
2. If the first marketing carrier is not specified on ATPCO’s published list of US DOT and CTA carriers, then the rules of the very next marketing carrier on the journey that is specified on ATPCO’s lists of US DOT and CTA carriers applies.
3. Once the first marketing carrier is identified (through steps 1 and 2 above), it is the first marketing carrier’s policy to opt for the rules of the most significant marketing carrier (MSC) for the journey or retain the first marketing carrier’s own baggage policy.
Cathay Pacific opts to use the most significant carrier rules.
So it depends whether AS adopts "first marketing carrier" or "most significant carrier" rules. If they adopt MSC then Cathay's rules apply since it has the trans-pacific leg and then you are correct that the baggage allowance would be 2 * 32kg for the entire journey (or 3 * 32 kg if she has CX Gold or above, or OW Emerald status).