As of my knowledge, EOSfit7 does not have the option to fit E-V data.

First of all, you go through the manual of any software and ensure what type of input can be used in those softwares that you wish to use.

EOSfit7 handles P-V or P-lattice parameters data as input.

If you wish to fit E-V data, you may refer the following web page for the different eos in which they relate the unit cell volume to the energy. fit your data to any of the equation and you can get the bulk modulus.

http://www.theochem.unito.it/crystal_tuto/mssc2013_cd/tutorials/eos/eos_tut.html

or, many scripts(python, fortran etc) are available in the web which can fit the E-V the data and give the parameters as output. Ensure it contains no error and use them to get the desired parameters.