Take some number of citizens C.

If the population of the state is P, let the number of Representatives (R) be P/C, rounded up [R=ceil(P/C)].

Note how land area is not a part of the formula.

If Texas were the size of Detroit while maintaining the total population size, would you argue in favor of reducing their representatives to 1 or even 0?

If the answer is yes, you need to take a civics class. Your question is like asking how much wax you need to make a crayon be blue; the hue of the crayon is entirely independent of the total amount of wax. Hopefully that's an analogy you understand.