GTA V Online Character Transfer PS3 to PS4

Solution 1:

It is no longer possible to transfer characters in GTA V.

As of March 6th, 2017 character transfers have been discontinued.

A Rockstar article also states:

Question: Can I transfer my character from my current platform to another?

Answer: No, this is not possible. There is currently no feature available to transfer character data between platforms.

There are no legal ways to transfer a character in GTA V anymore. Since the data for characters is online based, you'd be hard pressed trying to transfer a character by different means, if it's even possible. Support also states that if you attempt to transfer a character, nothing will happen.