How long does post-CoViD syndrome last? Can it be fatal (cause death) if you survived the disease prevoiusly?

Please elaborate "survived'. This could include people who had very mild symptoms, and others who may have spent weeks on a ventilator with severe lung damage. Both sets survived a first bout, but a second round of Covid will like kill victims who had more severe covid effects during their first round of sickness.

No one knows.  The disease is to new for anyone to know the long term effects.  

Also every person is different.  Just as some people can eat nuts all day ling without any effect, and others can have a fatal reaction to just one speak of nuts, so some people can get COVID and never have any symptoms.  While others will be sick for months and finally die from it.

There is no way to say how long it last as it is different for every person depending on how their body reacts to it.