Punctuation usage

Referent power means the ability of a leader to influence his followers and instill in them respect, loyalty, admiration, affection and a desire to gain approval.

Do I need to use punctuation after 'them' in the above sentence?

No punctuation is needed after "them".

"respect, loyalty, admiration, affection and a desire to gain approval" are the direct object of "instill", and you don't include a comma between a verb and its direct object. (Unless you have some parenthetical clause that requires to be offset by brackets.)

Merriam-Webster gives under instill the following example: "a charismatic leader who instilled in his followers a passionate commitment to the cause". This is the same construction, with the indirect object given by "in his followers" and the direct object "a passionate commitment". There is no comma here.