Yes, it definitely matters very much. If the tin is too large, the cake will be flat and shrunken. If it is too small, the cake will bubble or bulge up and over the sides of the tin.
However, the mixture for a round tin will fit a square tin that is about 2 cm smaller; for instance, a mixture that is designed to fill a 20 cm round tin can be used to fill a 18 cm square tin.
To adapt a recipe to fill a shaped tin, for example the number '9' for a birthday cake, fill your usual tin with water to the level the mixture normally reaches. Then pour the water into the new tin to the level required and estimate the quantity of mixture needed, doubling or halving the recipe as required.
** Asian Recipes