TOURIST VISA to Canada:
Assuming you are a Canadian Citizen, which might have an influence depending on a few details I will discuss down below.
Normally a TRV = Temporary Resident Visa, which is the Only option for a Tourist wanting to enter Canada in your case, is normally automatically granted a 6-month stay. Having said this, on special occasions, a Border Patrol Officer can Limit your stay with a Visitor Record where the Officer will Stamp her Passport with a Date when your Gf must Exit the country, but thankfully that rarely happens.
FIRST, every Applicant gets Evaluated and Approved on their own Merits, so the first things Immigration Officers look at are for your Gf to show:
#1- Ties to her country like a Property, a House, Land or a Business
#2- A good long-term job ( = more than 2 years) with above average paying job ( Minimum 35,000 Bahts per month and up)
#3- Travel history to Developed countries similar to Canadian Standard 😊 G20 countries )
#4 – If she travelled, did she respect the Visa obligations and was Not late to Exit the country
THEN, if you have a Common Law relationship of more than 2 years with a Property, a House, Land or a Business TOGETHER, Life Insurance with your GF as Beneficiary and vice versa as well as a Joint bank Account, then the Immigration Officer while taking this into consideration as a Joint Application which would help your Gf application a bit.
Keep in mind the Main focus of an Immigration Officer is to evaluate the Risk of an applicant staying in the country Illegally after the Tourist Visa expires which happens a Lot, so with the above-mentioned information, the main focus is to evaluate the risks of that happening.
Hope this helps and feel free to visit the Visa Canada website for more info.
*********************************************************************************************************************************************************************