how much boneless chicken breast and i use in place of 14 ounces of tofu in recipe

Without knowing what the recipe is it's a bit hard to say but you may want to substitute a similar amount (14-16 ounces). If the recipe is for four portions, that would be 3.5 to 4 ounces which I feel is a reasonable serving size for protein (either vegetable or animal).

Best of luck.