How can I get data from ResultRow object in views template
There are two question. First how to get the title in the kint dump?

{{ row._entity.title.value }} should work, also {{ row._entity.gettitle }} or {{ row._entity.label }}, because getTitle() and label() are methods of the node object.

Second, could anyone please help me how could I iterate through row data in views twig template?

In Views two steps are needed, first get the field and then use the method getValue() on the field providing the result row as parameter:

{{ view.field.field_name.value(view.result[0]) }}