No, they do not have to hold funds in reserve equal to face value of all the outstanding chips? .
Casino bankrolls are a complicated formula.
Number of slots, table, games, progressive jackpots, keno limits, sports book betting limits, chips in play etc, etc.

Once there is a reasonable expectation that missing chips are not coming back, profit from them can be brought into revenue, usually on Jan 1 after a year to year count. This will also help with the yearly inventory tax.