Under the US Code Title 2 section 192, contempt of Congress is punishable by "not less than one month nor more than twelve months" in prison. BUT, it requires the Attorney General's cooperation in prosecuting. Good luck with that under the Obama administration.
Under a Trump-appointed US Attorney, it may be different.
RE: BUT, it requires the Attorney General’s cooperation in prosecuting
There is a flaw in the law then. In the case of Obama’s administration, it was the Attorney General HIMSELF ( Eric Holder ) who was held in contempt.