'It has been' as in: It's been a long time. It's been days. or It's been a year. Mèsi boubout mwen :)

You can use "Depi ...." or  "Sa fè ...."

Depi de jou m pa wè w.
Sa fè de jou m pa wè w.
Mwen gen de jou depi m pa wè w.
It's been two days since I've seen you.

Depi twazan li malad.
Sa gen twazan li malad.
Li gen twazan depi l malad.
It's been three years since she's been ill.

It has been ...

Sa fè ...

Sa gen ...

Sa fè lontan depi mwen pa wè w.
Mwen gen lontan depi m pa wè.

It's been a long time since I haven't seen you.

Sa fè kèk jou depi mwen te dènye wè li.

Nou gen kèk jou depi dènye fwa nou te wè l.

It's been days since we last saw her.

Sa gen dezan depi m pa al nan plaj.

Mwen gen dezan depi m'ale nan plaj.

It's been two years since I been to the beach.

Sa gen twò lontan.
(Mwen) gen twò lontan.

It's been too long.

Sa gen lontan depi m te tande chan sa a.
Mwen gen lontan depi m pa tande chante sa a.

It's been a while since I heard that song.