There aren't very many compared to how many people you usually see there.
There are far fewer people crossing here compared to the usual number of people in Shinjuku.
このシチュエーションでの「いつもより少ない方だよ」は下のように言えるかと思います。
ーThere aren't very many compared to how many people you usually see there.
「いつもに比べたら全然多くないよ。」
compared to「比べると」
ーThere are far fewer people crossing here compared to the usual number of people in Shinjuku.
「新宿のいつもの人の数と比べると、ここを渡っている人の数は全然少ないよ。」
far fewer で「はるかに少ない」と言えます。
usual number of people で「いつもの人の数」
ご参考まで！
カナダ 
