This work examines the thermoelectric behavior of Germanene nanotubes (GeNTs) relative to Carbon nanotubes (CNTs), focusing on the influence of external factors, such as chemical potential and applied fields, on their thermal and electronic behavior. Through the application of the tight-binding model and Kubo formula, thermal conductivity, magnetic susceptibility and thermoelectric figure of merit are systematically analyzed. Findings reveal that GeNTs exhibit notable advantages in both thermal conductivity and magnetic susceptibility, particularly under the influence of external fields. Furthermore, the response of GeNTs to electric and magnetic fields is closely related to variations in nanotube radius and chemical potential which enhances their thermoelectric performance over a wider temperature range. These findings highlight the promise of GeNTs as favorable materials for thermoelectric applications in environments that require significant thermal and electrical performance.