If the beginnig of the sentense is in the present “je ne suis pas ici” you will not use future to describe where you are. You can use present to describe where you are or conditionnal for where you could be (il n’y a qu’un autre endroit où je pourrais être).
But the usage of the future could be right depending of the context.

It seems the title of the question is not proper; it seems it should instead be something such as

“Do the following English and French contexts correspond and what can be said of the tense of the verb? Is the future an option?”.

A_ The contexts do correspond.

B_ You cannot use the future; the present subjunctive is required here or the present conditional. However, the traditional use of the subjunctive is being supplanted nowadays by the present.

1/ Si je ne suis pas ici, il n’y a qu’un autre endroit où je puisse être.
2/ Si je ne suis pas ici, il y n’y a qu’un autre endroit où je peux être.
3/ Si je ne suis pas ici, il n’y a qu’un autre endroit où je pourrais être.

In “1/” there is a simple coding of a state that is not real (by means of the subjunctive); in “2/” there is some emphasis on the aspect of realisable possibility in the state that is conferred by the verb.