I am collecting OAS as well as GIS supplement. I may be receiving a cash inheritance from the sale of my father’s home in the USA. How will that affect my GIS benefit?

[TurboTaxBrenda1]

No, this will not affect your OAS or GIS. As this will be a cash inheritance it won't need to be reported. 

International tax specialist Gary Gauvin, EA, says that “inheritance of money, property or investments is not taxable income for Canadian residents, whether received from another Canadian resident or a foreign resident.” An inheritance that consists of cash only doesn’t have to be reported to the Canadian tax authorities when inherited directly from the decedent. However, if you take possession of “specified foreign property,” you may need to file Form T1135, Foreign Income Verification Statement. This form is used to declare ownership to the tax authorities if the property value exceeds what the CRA calls the $100,000 reporting threshold.