For the calculation, let's assume no modules/drones/pilots were used

A maxed Arthur has 522 600 HP with 170 Defense (63% damage reduction), which means its effective HP would be 851 838 HP. For comparison, a maxed Minos has 584 000 HP with 160 Defense (61.5%), it has 943 160 effective HP.

Typhon has 4x Igniters, and let's assume each Igniter is MK2 lvl 4. Each 2.4 Igniter has 137 200 damage per magazine. Multiply by 4 and you have 548 800 damage. That's already more than half of Arthur's HP gone within 10 seconds without all sorts of damage boosts.

Conclusion, Arthur's main survivability which is its shield is ignored, making it extremely weak. Other titans such as Minos can tank way more despite having similar HP to Arthur because it has a Reflector, Murometz has stealth and Nodens has increased defense when linked to an ally along with suppression.