Translation:He is here from the start of the crisis.
The standard translation, "He has been here since the start of the crisis" accepted.
It's perhaps worth noting that this use of the Present Perfect, with "since" and "for", is an exception, and is generally translated in Romance languages with the Present, rather than with a past tense.
Can someone explain to me why it is "crizei" and not crizele for this gen-dat agreement? I had a rule in my head (that I probably made up from incomplete conclusions) that if the feminine noun was a specific Person or Place, the final "a" of the word was replaced with "ei" and if it was a thing, the plural feminine form was used? And now I'm confused again