Such a question, or the assertion (that life has a value), smacks of absurd ridiculousness to me. Despite its implied appeal to 'objectivity,' it remains, within the confines of critical thinking, an example of begging the question. Put another way, it's a circularity; an implied valuation on valuation; values are valuable. Does this mean valuing is valuable? Anyway, there's a subtle shiftiness from activity (verb) to thing (noun) becomes which becomes apparent very quickly.
From another angle:
Say your interlocutor is named Bob. Is Bob living? Or does Bob somehow have 'life'? Does Bob believe 'Bob' is somehow separable from 'his life'? Where did 'Bob' manage to catch or seize 'life'? Or, conversely, how did 'life' pick up this 'Bob'? If Bob isn't irritable by this time, Bob, according to the demands of this logical play, should be able to define 'Bob' and 'life' unhesitatingly and clearly. Otherwise, Bob has just shown they're speaking gibberish while at the same time demanding clarity from you.
If such 'things' ('Bob,' 'life') cannot be 'defined,' then questions pertaining to 'value of life' may be seen easily as nonsense and hardly have anything to do with living and continuously re-valuing, or preferably (following my own penchant toward etymological broadening), re-worth-ing.
For me this kind of logical heel-digging comes across as nothing but a deep-seated fear and distrust in the messiness we call 'world.' Attendant with this fear/distrust, is the drive to shape 'the world' into something more malleable and controllable toward ends I desire to see perennially unrealized.