how long could a person spend in jail if i was found guilty by jury of a f1 kidnaping and 3 gsi f4 charges

There are a few different “flavors” of kidnapping in Ohio but I am assuming you mean the regular old Felony 1 Kidnapping that carries three to ten years in prison.  One count Felony 4 Gross Sexual Imposition is good for six to eighteen months in prison.  So if the judge were to “stack and max” (as we say in the trade) or give the defendant the maximum consecutive sentence that person is looking at 10 years on the kidnapping plus 3x18months (54 months or 4 ½ years) on the GSI for a grand total of 14 ½ years.  A lot of time to be sure.  That is a worst case scenario without knowing any of the particulars of the case; local attorney who knows the lay of the land should be consulted.   The information provided in this answer is provided for general information only; the information provided should not be construed to be formal legal advice nor the formation of a lawyer/client relationship. It is strongly advised you contact a lawyer in your geographic area to more fully discuss the issues raised in your question.