「私の父は会社役員をしています」= My father is an executive officer. / My father is an executive. / My father is an executive. / My father is a company executive. / My father is an officer at his company. などの組みわせは全て正しい言い方です。
しかし,特に偉い役員の場合,CEOおよびCFOを直接言っても問題ありません。
「私の父はCEOです」= My father is a CEO.
になります。
ご参考までに