When the amount of fluid in the spaces between cells increase, so does the pressure in these spaces. What do you infer will happen?

The fluid increases because of the increase in water. In this case, the cells will expand because of the water moving down its concentration gradient. I f the fluid is a gas then there is no pressure inside the fluid. Indeed, the pressure is a force applied per unit area by gas particles on any solid surface around it. It will be same everywhere.