I keep seeing in the news that, at the president's order, people are ignoring subpoenas from the house of representatives, citing executive privilege. So what legal bite does the president have if someone ignores his directive/order to not cooperate with the house; i.e., what can a president do legally, (Fine, Jail etc.) if he says they cannot testify and they do.
There are NO LEGAL consequences for obedience to a LEGAL subpoena.
Digging a bit further, a subpeona is considered legal if issued by an authorized (person/committee/court/ etc). It is Legal on it's face. A judicial review to consider quashing (suspending or eliminating or considering the subpoena ineffective) must be requested by the subject of the subpoena.
However, in the current clime, there are repercussions for defying "the boss". Defying Trump may cost you your current job, however that would not necessarily mean that your future employment with the Federal government would be lost.
There are no legal consequences if someone obeys a subpoena in defiance of orders. In fact there are potential legal consequences if they ignore the subpoena. Technically the people refusing to obey subpoenas (assuming the subpoenas are found valid in the inevitable court battles), even if the were ordered to refuse, can be charged with contempt and potentially thrown in jail.
The repercussions if they obey the subpoena are the usual ones you face if you disobey your employer - you can be fired and never hired by your employer again. And since there is only one Federal government, that effectively means the end of your career. And since you would incur the displeasure of the the President, other career opportunities might well be closed to you as well.