@ysmina-- There are certainly other factors that are weighed in when estimating the standard of living in a country. GDP is definitely a major factor, but there are others such as ownership of property and capital, access to education, services, technology and so forth.
Which of these factors are considered depends on the organization and they should specify how they have defined standard of living. But I cannot imagine anyone attempting to estimate the standard of living without taking into consideration GDP, which is basically the income of the citizens of that country.
It all goes together really. If people do not have enough income, they cannot purchase their needed goods and services. Similarly, if those goods and services are not available, people do not have access to them no matter how much income they have. All of these determine the standard of living.