Can i meet suicune after it escaped in pokemon leaf green and fire red?

Yeah, check your pokédex, you'll see it's current location. It moves about whenever you move to a different Route/Town/Dungeon though so expect it to take a while.

If it ever uses Roar and causes you to flee though you'll never see it again. Best reload your file if that ever happens.

good luck catching it, I'm still after Entei on my FireRed...

Yeah you can. You just have to check your pokedex and it will show its location. But be warned it moves around ALOT so sometimes it wont be in that location when you get there. My advice is go to a place where 2 different locations are right next to eachother and every once in a wile suicune will be there. But you should weaken it first cuz if you weaken it it's health stays that way, so you should weaken it and then when it has red health, bring a high lv pokemon that knows sing or hypnosis and put it to sleep then try to catch it.