What to do?
Build infrastructure. I don't think we can win a war of conquest against kaz and I'm not sure that if we do win it, we'll be all that happy.
Right now, we have 3 cities who are a drain on our economy, in PM, TKY and Zero. We have very little infrastructure in our good cities to offset that - no courts, no markets, and we are building 2 (soon 3) wonders. (moai, heroic epic and palace) If we invade kaz and take cities, they will be a bigger drain on our economy - if we raze them, then we aren't expanding.
We need more workers. We are already stretched and we haven't yet made any of the improvements we want to make at TKY.
We are behind on tech - OR, CS and machinery. We are up music and lit (on cav) - Kaz has feudalism, so if we do attack, we'll face LB's. They are able to tech engineering, so will be able to have pikes. Or, they might go paper and bulb education, allowing the to build their cheap unis
If we do land a stack in Kaz lands, we'll be hit by cats and horse archers with double flanking to kill OUR cats. We'll lose units try to take LB's in a city on a hill with injured units. Our reinforcements will take a long time to get to Kaz, where their reinforcements (on 3 move roads) will take very little time to get to us.
If Kaz keeps attacking us, they'll get weariness. If we attack Kaz, WE'LL get weariness.
We are still fighting barbs - we have land between cities that need to be fog busted. We really don't have any backline cities.
If we try to attack Kaz and start to succeed, I am reasonably sure Cav will attack - best case, they come across land. Worst case, they beeline optics and drop units in our north east.
With 10 turns of infrastructure builds and teching... yes, we can start thinking about taking the fight to Kaz, maybe - but I think we need a few more cities and a lot of infrastructure....