When exactly we should use depuis with present?

Question

Answer

Bonjour Jayani,

You use "depuis* with the present tense when you're talking about something that started in the past and continues in the present.

For example,

J'habite ici depuis 5 ans - I've lived here for 5 years.

Je travaille depuis ce matin. - I've been working since this morning.

Answer

I feel that 
  J'habite ici depuis 5 ans 
translates to 
  I have been living here for (the past) 5 years
rather than
  I've lived here for 5 years.
See
https://www.usingenglish.com/forum/threads/71092-quot-I-ve-been-living-quot-vs-quot-I-ve-lived-quot
https://english.stackexchange.com/questions/84898/have-lived-vs-have-been-living

Answer

Can you use depuis with the passé composé in the affirmative?

How would you say if something has happened since a particular time? For example, when I translated I saw him one since last week it came up as Je l'ai vu une fois depuis la semaine dernière.