I've read 2-5% of GBS patients do not survive the onset or short-term complications, usually due to respiratory failure. Though the long-term complications from GBS can definitely impact longevity, I haven't seen any statistics that define exactly why life expectancy was shortened. But the GBS patient may suffer poor balance, poor strength, poor stamina, poor sensitivity to touch or temperature. So it's easy to foresee that GBS patients may have increased likelihood to experience serious injuries (ladder falls, stairs falls, bathtub falls), or sometimes fatal accidents (driving, swimming, bathing), or death due to complications from those & other accidents. Others will get fully well from GBS & as far as I know experience normal longevity.