a) California state employee salaries are online [1]
b) UC Berkeley is a top school for CS professors and competitive with everyone else on salaries. Looking at random AI faculty members shows about 100k at hiring, about 150k at tenure, while machine learning king of kings Michael I Jordan gets 300k.
Google pays starting undergrads > 160k, and fresh PhD students > 225k[2] (all in comp including first year vesting stock + base pay + expected 15% bonus). I imagine if they're poaching faculty, they're getting significantly more than that[3].
Basically I'd say the industry salaries are at least 2x the academic salaries, if not higher. The flagship hires are paid a lot more (think Yann LeCun, or Andrew Ng), and importantly, given the freedom to hire and build mini-empires to do stuff.
As a final note, I know talking about salaries publicly is awkward, but this is all public information, and grad students talk freely about this sort of stuff with each other, so I don't feel like I'm revealing anything super secret beyond showing you how to look up the relevant information in publicly available areas.
[1]: (http://www.sacbee.com/site-services/databases/state-pay/arti...)
[2]: Source: Glassdoor Google for "research scientist", which is the position that PhDs in AI/ML are hired into.
[3]: Google levels are public, and while Glassdoor data is sparse, faculty who are poached are hired at at least the "senior staff engineer" level, which glassdoor says about 500k, which sounds around right to me, if not a little low. As an aside, salaries at the higher levels have much higher variance than at the lower levels, and to entice someone away from a tenured position probably requires hitting the higher ends of the salary band.