It does not, but Twin Attack would grant another attack.

A quick tutorial on why it works that way (along with explanation of some terms)...

During an activation:
1. The character is considered activated.
2. The character takes a turn.

During a turn, a character gets these two options in either order:
1. The character gets their normal attack.
2. The character gets to move. (Moving their speed if they attack this turn or double speed if they do not.)

Furious Assault is a Replaces Turn ability, so in order to use it the character gives up the whole turn - both their normal attack and their normal move.

Greater Mobile Attack grants two bonuses. First, the character's normal move can be split into two parts with the attack in the middle. Second, during the character's normal attack, they can use multiple attacks even though they moved. But when using Furious Assault neither the normal move nor the normal attack take place, so GMA has no effect.

Twin Attack, however, grants a bonus whenever a character makes any attack - whether it's an attack as part of a normal attack action or an attack that is generated by a Special Ability (except the attack generated by Twin Attack itself). Furious Assault grants attacks, so Twin Attack triggers for each attack generated by Furious Assault.