You are not even living in Pakistan, how would the visa officer believe you will leave Canada and return to Pakistan after your studies?let's assume i apply from Pakistan but it will be more complicated because, I don't have an active job/salary etc, so it will definitely make VO thinks that I am trying to get there by any mean.
i am sure someone has gone through this hassle and there should be a result, as i don't have any other objections like non-financial /family ties/ relation to the country, as per my research on this forms i found people do have 5 to 6 reasons with indicating family ties and ties to the home country.
i have to find someone who went through this process and how he/she overcome this.
There is no 100% guarantee that you will be allowed back into Saudi Arabia after you leave for Canada and complete your studies, since you're not a citizen of Saudi Arabia.