You're very likely correct, Alfred. A Finnish name site linked to this site (through Eponym, which shows many namesites by nationality) says that Tuija means "tree of life", or arborvitae, an evergreen which grows in southern Finland (as well as elsewhere, including the US, as an introduced specimen plant). The site says that Tuija is of fairly recent usage (last 50 years) as a female name.
Mike C - I'm not sure I want to quibble with anyone who apparently knows Finnish. Maybe one of our Finnish regulars could confirm?