The employer needs to get a labour market opinion to be allowed to hire a foreigner. That can take from a few weeks to a few months even depending on the situation. If he is from a visa exempt country, he can apply for a work permit at the border if he has the LMO. Otherwise, he has to apply at the embassy and usually it doesn't take too long to get the work permit once you have the LMO, couple of weeks.
A work permit is valid for the duration of the contract but no more than 2 years. If his job is classified as a skilled job, he can apply for permanent residency through a provincial nominee program with the help of his employer right away or after 2 years, extend the work permit and apply for permanent residency through Canadian experience class without the help of his employer.
If it is not classified as a skilled job, he normally would not qualify to apply for permanent residency unless he is doing certain listed jobs in BC or AB. On a low skill permit, after 2 years he would have to leave for 4 months before being allowed to apply for another low skill permit unless he could get a skilled job and change of work permit in the meantime or his employer can upgrade him to skilled.
