The character will be available for you to download sometime in Spring 2018. Just like in the game, Noctis can use a multitude of weapons depending on his inputs, as well as throw his weapons to warp from one part of the stage to another.
"Noctis Lucis Caelum from Final Fantasy XV enters the Tekken 7 ring", Bandai Namco detailed in a blurb accompanying a gameplay trailer. Other points to note while the World Tour Finals are on today are that Geese Howard is nearly completed for the DLC release and they are moving the game over to a newer version of Unreal Engine.
The news first broke in San Francisco at the finals of the Tekken World Tour, an esports tournament that's been raging since the game's console release in June. Other Final Fantasy XV characters shown on the Hammerhead stage include Noctis' party, some Chocobos, Cindy and other NPCs. The top 16 Tekken players battled for a $50,000 prize and the competition streamed on the official Tekken Twitch channel.