Is gasoline a homogeneous compound or a mixture?

It is a homogenous mixture, because it is a mixture of a few different hydrocarbons.

A heterogeneous mixture is one that consists of two or more substances; it is non-uniform and the components of the mixture can be seen. Vegetable soup is an example of this type of mixture.

A homogeneous mixture has uniform composition and properties throughout. Salt added to water and stirred until it dissolves is a heterogenous mixture. Air is a homogeneous mixture of gases.
Gasoline like most clear liquids is homogenous (of one nature or of a uniform nature). Windex, blood and milk are other examples of homogenous mixtures.

Heterogenous mixtures are anything that is not uniform in its composition, some everyday examples are: sand in water, vinegar and oil, and a bowl of oatmeal.