Mark Jones, 43, who had been in hospital since the incident on 26 July, died on Saturday.
Two men have been charged with attempted murder and having a shotgun following the shooting on New Road, Mountain Ash.
South Wales Police said a review of those charges would now take place.
Edward Bennett, 47, from Mountain Ash, and Stephen Bennett, 52, from Pontypridd, were both remanded in custody after appearing at Cardiff Crown Court in August.
Det Ch Insp Ceri Hughes said: "Our thoughts are with Mark's family who are being supported by a family liaison officer at this difficult time.
"A review of charges in relation to the two men in custody will now take place."
A man who was in a critical condition after a shooting in Rhondda Cynon Taff two months ago has now died, police said.