Gilmans and carbon dioxide
Yes, cuprates do react with carbon dioxide to give access to carboxylates / carboxylic acids.

Running a SciFinder search, I do not see any examples of traditional Gilman reagents (alkyl cuprates) reacting directly with carbon dioxide. This shouldn't be surprising though, since the alkyl cuprates are generated from the corresponding alkyl lithium compound. If you have the alkyl lithium compound, then you can just react that with carbon dioxide directly.

A more synthetically useful situation is when the alkyl cuprate is reacted with an alkyne, resulting in a syn-addition of the alkyl group and copper across the alkyne. The alkenyl (vinyl) cuprate can then be trapped with carbon dioxide to give a carboxylate.



A couple examples from the literature:

Z,​Z-​Dienes via acetylene carbocupration:  synthesis of navel orangeworm pheromone

The silylcupration of acetylenes: a synthesis of vinylsilanes

Also check the write up in Organic Reactions by Lipshutz (the world's expert in organocopper chemistry).

More complicated (non-Gilman) organocopper compounds have been reacted with carbon dioxide to give copper carboxylates:

Carbon-​carbon coupling of activated alkanes with carbon dioxide by [(phen)​(Ph3P)​Cu(O2COH)​]

Synthesis, Structure, and CO2 Reactivity of a Two-​Coordinate (Carbene)​copper(I) Methyl Complex