[imardmd1]

In this phrase, both verb forms are in the present tense:

το πνευμα εστιν το ζωοποιουν

the spirit is that which is the continuously-absolute-life-giving (begetting/Thayer?) one (present participle as predicate neuter singular articulate noun, embodying a sense of activity)

(but, comparatively)

η σαρξ ουκ ωφελει ουδεν

the flesh exists (emphatically not) continuously=ever benefits=contributes nothing=(not anything)

That means, rephrased, as I take it:

the literal, material flesh is never, no not ever, contributing anything.

Hm, Spring?

[imardmd1]

Correction in tense:

the flesh exists (emphatically not) continuously=ever benefits=contributes nothing=(not anything)

corrected:

the (literal, material) flesh never, no not ever, contributes anything.

(That is, it is dead.)