Italian uses present tense da time expressions to indicate an action that began in the past and is still going on in the present. English, by contrast, uses the present perfect tense (I have spoken, I have been working) for time expressions.
verb in the present tense da length of time
Scio da un anno. (I’ve been skiing for a year.)
Prendi lezioni di karatè da molti mesi. (You’ve been taking karate lessons for many months.)
To ask how long something has been going on, use da quanto tempo verb in the present.
Da quanto tempo leggi questa rivista? —Leggo questa rivista da molto tempo.
(How long have you been reading this magazine? —I’ve been reading this magazine for a long time.)