Well, there chances for extended survival is not exceedingly generous, according to the FARs 91.509 and 135.167. Bear in mind that it probably wouldn't take so long for a larger aircraft before they notice that it was missing.
(a) Except where the Administrator, by amending the operations
specifications of the certificate holder, requires the carriage of all
or any specific items of the equipment listed below for any overwater
operation, or, upon application of the certificate holder, the
Administrator allows deviation for a particular extended overwater
operation, no person may operate an aircraft in extended overwater
operations unless it carries, installed in conspicuously marked
locations easily accessible to the occupants if a ditching occurs, the
(1) An approved life preserver equipped with an approved survivor
locator light for each occupant of the aircraft. The life preserver
must be easily accessible to each seated occupant.
(2) Enough approved liferafts of a rated capacity and buoyancy to
accommodate the occupants of the aircraft.
(b) Each liferaft required by paragraph (a) of this section must be
equipped with or contain at least the following:
(1) One approved survivor locator light.
(2) One approved pyrotechnic signaling device.
(3) Either— (i) One survival kit, appropriately equipped for the route
to be flown; or
(ii) One canopy (for sail, sunshade, or rain catcher);
(iii) One radar reflector;
(iv) One liferaft repair kit;
(v) One bailing bucket;
(vi) One signaling mirror;
(vii) One police whistle;
(viii) One raft knife;
(ix) One CO2 bottle for emergency inflation;
(x) One inflation pump;
(xi) Two oars;
(xii) One 75-foot retaining line;
(xiii) One magnetic compass;
(xiv) One dye marker;
(xv) One flashlight having at least two size “D” cells or equivalent;
(xvi) A 2-day supply of emergency food rations supplying at least
1,000 calories per day for each person;
(xvii) For each two persons the raft is rated to carry, two pints of
water or one sea water desalting kit;
(xviii) One fishing kit;
(xix) One book on survival appropriate for the area in which the
aircraft is operated.
So I'd guess the answer is around three or four days perhaps. If they got to the galley onboard within an hour before the aircraft flooded, they might have a bit more...