You can get a copy of his Record of Employment from Service Canada - depends on how he was paid - if he was paid bi-weekly, the hours are listed for the pay period.http://www.servicecanada.gc.ca/eng/ei/employers/roew.shtml
Paystubs sometimes have that information. The number of hours per week should also be specified in the LMO and/or job contract or job offer letter.
Note that it doesn't matter if he works more than 37.5 hours per week - that's simply full-time.
Also note that you will have to get a Letter of Employment from the former employer, stating the hours worked per week (among other details - see the Document Checklist). If he is salaried and records are not kept by hours worked, it is then based on what the employer states in the Letter of Employment (as well as the LMO).http://www.cic.gc.ca/english/pdf/kits/forms/IMM5610E.PDFhttp://www.cic.gc.ca/english/information/applications/cec.asp