Be a full cabenet member and Exec branch IT department head
A CTO/CIO that is only a policy advisor with no department is pretty easy to marginalize in an organization as large as the US executive branch. For this reason the position must be a full cabenet member and department head with a staff, budget and mission.
The position must be the head of an executive branch Department of Information Technologies with a title like Secretary of the Department of Information Technologies rather than CTO or CIO. The department must have administrative and executive responsibility over the full life cycle of executive branch information systems, providing advice, expertise, implementation, operations monitoring and system audit support to other government departments. Projects and operations of the Department of Information Technologies require congressional approval and oversight similar to any other department of the executive branch.