My finance-foo is quite weak, what does advance dividend mean in this context?

Early repayment of some percentage of the uninsured deposits, prior to full liquidation and/or acquisition. Depositors have first access to funds either way.

From an FDIC guide [1] I found:

"advance dividend: A payment made to an uninsured depositor after a bank or thrift failure. The amount of the advance dividend represents the FDIC’s conservative estimate of the ultimate value of the receivership. Cash dividends equivalent to the board-approved advance dividend percentage (of total outstanding deposit claims) are paid to uninsured depositors, thereby giving them an immediate return of a portion of their uninsured deposit. Sometimes when it is projected that all depositor claims will be paid in full an advance dividend will be provided to unsecured creditors."

[1] https://www.fdic.gov/bank/historical/reshandbook/glossary.pd...

Management at the now FDIC-controlled bank will estimate the value of SVB’s assets, such as loans and bonds, and give depositors a fraction of that value to be paid in advance of the sale of those assets. They do this to prevent the collapse of all those companies who were SVB clients, which would be bad for the economy.

most likely a partial payment - i.e. you have 500K in the bank, 250K is insured and you know you will get it back - the other $250K nobody knows how much will be available when the dust settles, but maybe they (FDIC) feels confident they can give you 10% of that now, and keep making more payments as the picture becomes clearer on how much you can eventually get back. You won't get any final payments for many many months when everything is fully resolved.

And they'll probably get 90%+ back eventually. The bank's money isn't gone it just isn't liquid.

It could definitely be less than 90%. But yeah, it's not just poof gone.

I think 100% is more likely than below 90%