People say very few in comparison to the actual PCAT, there really isn't an exact number to be honest with you. However, definitely look over the practice tests as you may see a few questions that came straight from the practice (this is just from compiling numerous opinions throughout the forums from those who have taken it)
I would not rely on memorizing similar types of questions presented on the Pearsons exam for the PCAT.
Doing the Pearsons exam over and over again imo is very detrimental to your learning process because it is teaching you to memorize and regurgitate; and not necessarily to comprehend and think fast on your feet (which is what the PCAT is all about).
By the time you've taken the Pearsons exam for the second time, you've basically memorized all of the questions already and your brain isn't in thinking mode but recall mode. This will not do you any good on the actual exam.