Assuming that all your employers deducted taxes from your paycheck, and that you haven't had any sources of income other than employment then it is most likely that the Canada Revenue Agency owes you a refund, rather than you owing them money.
In Canada it is not illegal to file a tax form late (as late as you like) provided you do not owe taxes. Therefore (subject to the conditions above) you have probably not committed any kind of crime. However you have let the government keep money that is due to you.
It is unlikely that this will affect your application for citizenship. Citizenship in Canada is fairly automatic provided you spend the requisite time in Canada.
However I do strongly recommend that you file all your back taxes as soon as possible. This should remove any doubt as to whether there is a problem. It may also get you some extra money. There is absolutely nothing to be gained by delaying. Get a tax preparer to work out taxes for all your years in Canada before you send them off. If they all show you deserve a refund them send them off and wait for the government to send you money. If any show that you owe money then ask your tax preparer for advice, or maybe engage a lawyer to ask what to do. Tax lawyers are good at negotiating with the CRA in circumstances like this. It is likely that if you are prepared to pay any tax you owe immediately then the consequences will not be serious.