Were Maria Theresa of Austria and Napoleon alive at the same time?
Yes. Maria Theresa of Austria and Napoleon were alive at the same time for 11 years, from 1769 to 1780.
Maria Theresa of Austria was 52 when Napoleon was born.
Napoleon was 11 when Maria Theresa of Austria died, aged 63.
Maria Theresa of Austria
Ruler of the Habsburg Dominions
Born 13 May 1717 · died 29 November 1780, aged 63
Napoleon
French military leader, French Emperor 1804–1814 and again in 1815
Born 15 August 1769 · died 5 May 1821, aged 51