Ruiz, who turned 54 on May 29, had been comatose at East Jefferson General Hospital since he fell early May 19 in front of a French Quarter bar.
He died about 3:50 a.m. Tuesday, agent Joel Chriss said in a telephone interview from New York.
Ruiz, of Teaneck, N.J., has been described as one of the most versatile musicians in jazz, playing bop, Afro-Cuban, stride and many other styles.
"He's one of the few musicians on the scene that is equally at home in both the jazz genre and the Afro-Cuban genre in a complete sense. ... He really can play the blues, too. For real," trombone player Steve Turre, who had known Ruiz since 1975, said in an interview the week after Ruiz fell. "There's a lot of people who dabble with both worlds. But very few can authentically deal with both. And he's one of them. That's your rarity."
He described Ruiz as a complex man and a brilliant musician, a pianist, composer and bandleader of genius.
Ruiz came to New Orleans with Marco Matute, a producer for the M27 World label, to shoot video to go along with a Hurricane Katrina benefit compact disc of New Orleans music, attorney Mary Howell said before his death. They arrived May 18, she said.
"They spent the whole day filming, riding in carriages, talking to people about New Orleans," She said.
She said Ruiz "got very involved in the situation here" after playing in a New York benefit concert for the hurricane's victims.
The family has been "inundated with calls from people wanting to help." They asked for prayers; an account to help pay Ruiz' medical expenses was set up, Howell said.
Trained in classical music as well as jazz, Ruiz played at Carnegie Recital Hall when he was 8 years old. His teachers included jazz pianist and composer Mary Lou Williams; in his early 20s, he and Turre both worked with saxophone player Rahsaan Roland Kirk.
In an interview with Ted Panken, for liner notes on his 2003 CD, "Enchantment," Ruiz said Kirk - known, among other things, for playing a saxophone and two of its turn-of-the-century cousins at once - nurtured and demanded versatility.
"All the music I enjoyed was part of the Rahsaan experience," Ruiz told Panken. "He played the music of Fats Waller and James P. Johnson. Real down-home blues, as they're called. The great composers of classical music. Music from all over the world - Africa, the Orient, the Middle East. We had to play all these musical flavors every night."
He was playing with Latin groups in his early teens. His first recording, at age 14, was with a group called Ray Jay and the East Siders. While still in his teens, Ruiz worked with tenor saxophonists Frank Foster and Joe Henderson and trumpeters Joe Newman, Freddie Hubbard