Do villages take the Y-Axis into consideration? [duplicate]

The answer is yes, villages do count y axis in distance.

I have built multiple smaller(single village) iron farms one above another above another in stacks. This allows me to load several at once and use the same killing/storage system for multiple farms without the village chaining problems of the iron titan.

The number 70 blocks is a little more complicated which has already been covered in this question: Click Here

For positioning of the titan, I recommend reading this question: Click Here. If done incorrectly, you could build it all correctly and as soon as it unloads, it recalculates the villages and ruins what you are trying to do. More details can be found in this wiki on village chaining: Click Here