Part of the ongoing Verse Quick Reference project.

Job 14:5 Since his days are determined, and the number of his months is with you, and you have appointed his limits that he cannot pass,

Job 14:5 is often used as a prooftext for the idea that God decides the length and extent of each individual’s life.

6. IT IS UNIVERSAL OR ALL-COMPREHENSIVE. The decree includes whatsoever comes to pass in the world, whether it be in the physical or in the moral realm, whether it be good or evil, Eph. 1: 11. It includes: … (e) the duration of man’s life, Job 14: 5; Ps. 39: 4…
Berkhof, Louis. Systematic Theology (p. 92). . Kindle Edition.

The verse, in context, is a quote by Job in the context of lamenting God’s misruling of the world. Job tells God to “look away” v6 because He is too harsh. The verse is better taken to mean that human kind does not live forever. God has set limits on how long man can live. And the point, in context, is that God should stop tormenting Job and let Job live out the remained of the lifespan determined for humans.

David Clines writes on Job 14:5:

5–6 The three cola of v 5 are best taken as the threefold reason for the demand of v 6. The initial [Hebrew omitted] is not the hypothetical “if” but “if, as is the case,” which means “since.” The emphasis in this triple description of the prescribed length of human life is not that it has been fixed at a particular span, nor that God himself has fixed it, but that God well knows how brief a span it is; this is so evidently the general reference that it is not expressly stated. Instead, what is stated is the impossibility of the assigned span being exceeded. The number of human days is “determined” [Hebrew omitted], the accent being on the irrevocability of the divine decree (Horst; cf. [Hebrew omitted] in Isa 10:22; Joel 4:14 [3:14]; Dan 9:26, 27; 11:36). Likewise the months of human life are “known” to God, lit., “with you” [Hebrew omitted], in your knowledge or memory; for such a meaning of [Hebrew omitted] “with” cf. Isa 59:12; Prov 2:1; Gen 40:14 (BDB, 86 § 3b). Days and months together add to a total which is humankind‘s “limit” ([Hebrew omitted] “prescribed thing”); the term is used in v 13 of a prescribed time, and elsewhere of the prescribed limit of the sea (26:10; 38:10; Jer 5:22; Prov 8:29), of the heavens (Ps 148:6) and of the land of Israel (Mic 7:11). To “pass over” [Hebrew omitted] a “prescribed limit” [Hebrew omitted] sounds like a legal expression meaning to “transgress a decree” (the exact phrase is not actually attested in the Hebrew Bible); some play may be made with the idea that any “overstepping” [Hebrew omitted] the divine prescription of one‘s fixed span of life would be like a “transgression” [Hebrew omitted] Job has twice urged God to “desist” [Hebrew] from him, to leave him alone (7:16; 10:20), so that he may have some relief in the days that remain for him. The thought is apparently a conventional form of lament; cf. Ps 39:14 [13] “Look away ([Hebrew omitted] , as here) from me, that I may be cheerful ([Hebrew omitted] , as in 9:27; 10:20), before I depart and be no more.” Here of course it is humankind, not Job personally, that is the ostensible object of God‘s unremitting attention, which Job experiences as hurtful and undesirable.