Translation:He has made his wife very happy for years.
"Depuis ("since" or "for") can be used for things that are still happening, and it's usually followed by a start date or a duration. It's tricky because a French present-tense verb with depuis often translates to an English present perfect verb.<pre>
Il pleut depuis hier. — It has been raining since yesterday. Je te connais depuis deux ans. — I have known you for two years."</pre>
See https://duome.eu/tips/en/zz [Search for depuis with Ctrl-F or Cmd-F]
Barbara has used the present perfect continuous tense - which could also have a similar meaning in this example - but used here in English is the present perfect: "He has made ..."
The present perfect is used to indicate a link between the present and the past. The time of the action is before now but not specified, and we are often more interested in the result than in the action itself.