How much should I spend in 8 days trip to Canada alone I intend to re-apply also about funds I'm working in multinational company with salary 15k EGP and has balance with 3500 $ +150k EGP
150K EGP is roughly 4500 CAD. So you have a saving of 8000 CAD. And an income of 450 CAD per month. That does look a bit of bridge too far.
To be honest, it makes your entire trip look very suspicious. Just round trip ticket from Cairo to Toronto cost 1K CAD per person. From toronto to Niagra fall, just bus fair will be 60 dollars per person each way. Add to that hotel room will be minimum 100 dollars per day. Food will be another 50-60 dollar each day. And site seeing is extra.
You are looking at an easy 2000-3000 dollars bill for an 8 day trip for one person. It will be very hard to justify that you will be spending 1/4th-1/3rd of your total savings (which are about 1.5 years worth of your earning) in touring Canada.
Now if you add wife and 2 childred....
Half of your saving is gone in air tickets only...
It looks a very extreme expense to me and very hard to convince why will you want to tour Canada while completely spending your 1.5 years worth of salary in savings.