He had been in hospital since the incident in Blanchardstown.
Gardaí have launched a second murder investigation following the death of the man who was shot in a restaurant in Dublin on Christmas Eve.
48-year-old Jason Hennessy was pronounced dead at the Mater Hospital today.
His alleged attacker, Tristan Sherry, was stabbed to death during the incident, and three people have been arrested in connection with his death.

Two Teenagers Arrested For Wrong-Way Driving Of A Stolen Car And Ramming Garda Vehicle
Taoiseach Travelling To UK For Meeting With Prime Minister
Man (50s) Due In Court Charged With Healy Rae Assault
Rathangan Will Be The Host Of Next Year's National Ploughing Championships
School Absence Increases In Last Ten Years
Timolin Student Awarded For Sepsis Research
Kfm and Independent Radio Stations Launch Major Road Safety Promotion
Central Bank Reveals Average Time Of Four Years To Build House