Basically what Moi Magnus said. In this case, the Pacal is dead or dying. If he isn't or you aren't at least trying to make him so, taking Autocracy was a mistake as you took a tree that doesn't fit the situation or your plan. Every city Pacal loses to your warmongering is one that cripples his Science and Culture as he probably has close to every building built there. The only thing that really helps you get the cultural victory in this case is making your opponents weak through fighting, and if you do so then the tourism merely speeds it up a bit, as the pitiful remains of the enemy's empire wouldn't be likely to win anyway - well, unless you've started the conquest so late he was on his last spaceship parts anyway. If he's that far in and so much ahead, I doubt anything can help outside of nuking him to death.
If you're at +100 warscore, the enemy is getting completely steamrolled by you. It doesn't matter how influential you are over someone who is on his last breath anyway as you can get his capital whenever you want, and if they're someone who's had lots of culture throughout the entire game, taking the capital will be faster anyway. Free Great Person of your choosing is a thing in Aesthetics already IIRC, and this late in the game the choice is an illusion as you will always take the Scientist anyway. Still, the T2/T3s should go to their own threads, there are some to necromance.