You can theoretically employ an unlimited number of people during the four year validity period of the sponsor licence.  Under the Skilled Worker visa scheme, you need to meet the Skilled Worker visa points requirement, obtain a Certificate of Sponsorship for each Skilled Worker visa applicant and pay the relevant Government fees.  The main requirements for an Intra-Company Transfer visa are a bit different to the Skilled Worker visa, with a salary requirement of £41,500 per annum in most cases and a smaller number of skilled occupations that qualify.  It will most likely remain the case that the Skilled Worker visa category will remain much more popular than the Intra-Company Transfer visa.  You should also make sure that you comply with your obligations as a sponsor licence holder.  If you do not do so, you could lose your sponsor licence.