This depends on the size of your drink. According to Grounds to Brew, there are 3 pumps in a tall (12 oz), 4 pumps in a grande (16 oz), and 5 pumps in a venti (20 oz).
Unlike the hot version, an iced venti mocha is 24 ounces and therefore has 6 pumps of mocha sauce. There is also a “short” option in hot drinks only. It is 8 ounces and has 2 pumps of mocha sauce.