Often yes, since location, hours and income shape household life more than the immigration category does. Eligible spouses and unmarried children under 21 may seek E dependent classification, but that follows the principal case. Discuss where the family would live and what each adult expects to do before committing capital to a venture in a particular place.
Ask what a spouse intends to do here
If the spouse plans to work outside the enterprise, note that a qualifying E spouse is generally employment-authorized incident to valid status, with proof such as an E-2S notation or the I-94 record; dependent children receive no work authorization. If instead the spouse would help run the business, decide early whether that is as an owner or an employee, because ownership affects the nationality and control analysis of the enterprise itself. Where a spouse would work inside the enterprise, resolve the ownership question before anything else is decided, because it changes the analysis of the business rather than only the household.
An owning spouse's nationality counts toward the enterprise's treaty character and may affect who is properly the investor; an employed spouse's does not. Neither arrangement is preferable in the abstract, and the right answer is the one that matches how the business will actually be run. Unmarried children under twenty-one may be included as dependents either way and receive no work authorization from that status.