He studied under Gustav Courbet, and perhaps this painting of peasants breaking ice reflects that. Les Briseurs de glace is not derivative; it is an impressive work of art.
Pantazis did not follow the pattern of Greek artists in the 19th century. That context, typified by Ottoman style and religious iconography, was breaking up when he went to Paris. According to this survey of 19th century Greek art, most aspiring artists at that time settled in Munich.
I am not sure when he painted this lovely portrait. He had settled in Belgium where he was part of a circle that included Guillaume Vogels, and Louis Dubois, who like him had studied with Gustave Courbet. One reads his work was well received in Belgium. The portrait is by a major talent --- that cat is posed realistically and the child is not a figment, but was once well loved.