。、。
All people are destined to die. However, when and how one dies cannot be decided.
Literal
All [genitive-の] people [topic-は] die fate [to-にある]. However, when die [question-か] how die [question-か] [topic-は] cannot-be-decided.
Two short, punchy philosophical sentences. 死ぬ運命にある ('to be in the fate of dying') is a set pattern: noun + にある meaning 'to be in X state.' The second sentence embeds two indirect questions with か — いつ死ぬか ('when one dies') and どのように死ぬか ('how one dies') — and then predicates them with 決められない (potential negative of 決める: 'cannot be decided'). The philosophical weight comes from the contrast: death is certain, but its timing and manner are not.