Eligibility is automatic with her marriage - but she would NOT have acquired Swiss citizenship unless she VOLUNTARILLY applied for it.
LINK to Swiss Gov't webpage on Citizenship through marraige:
Excerpt:
Facilitated naturalisationGo to page «Naturalisation»
Foreign spouses of Swiss nationals who have lived in Switzerland for a year may apply for facilitated naturalisation after three years of marriage, provided they have lived in Switzerland for a total of five years. People who have close ties with Switzerland may apply for facilitated naturalisation even if they are resident abroad. In such cases, however, they must have been married to a Swiss spouse for at least six years.
Applicants are: particularly foreign spouses of Swiss nationals and foreign children, one of whose parents is Swiss
Application to be submitted to:
Confederation
FOM, Naturalisation Section, Quellenweg 6,
3003 Bern-Wabern
DUAL CITIZENSHIP = DIVIDED LOYALTY (For the Right as well as the Left.)