There is nothing stopping you from trying the student visa route. However you'll want to make sure that your wife looks like a genuine student and not just like someone who is using a study visa as a means of getting into Canada. I would strong recommend against applying for a student visa just to study English in Canada. These applications have a very high rate of refusal since this is the route many non-genuine students try to take.
If she wants to have a try at applying, it should be for a multi-year degree or diploma program (university degree is preferable). The program she selects must also make sense in terms of her past education and any work experience (e.g if she completed a bachelor in her home country with a business focus, an MBA would be the next logical step). Note that it's too late to obtain a study permit for the January intake at this point. So you would be looking at May for the start of her classes. The first step is to apply and be accepted by a college or university program in Canada (note that not all programs have May intakes). Make sure you check out the Designated Learning Institution list on the CIC web site to verify the school is recognized by CIC (study visas are only granted for recognized schools).
To be approved, your wife will also need to demonstrate that she has sufficient funds to pay for her tuition and living expenses. This will involve showing a bank balance of first year tuition + $10k living expenses + $2-3K for travel expenses. I'm sure you've already seen that tuition for foreign students is substantially higher than that for domestic students. So the bank balance she will need to show will be $20K minimum (likely higher).
