Not yet. Not by a long shot.
In two ways:
1) Donations don't come in on their own. You have to pay staff to go out and bring them in, track them, follow up on them, tax-receipt them, etc., as well as the facilities and infrastructure to support that staff. TCU, not Athletics, pays for all of this.
2) Most donations of any size aren't funded in a lump sum, they're funded over a term of years -- usually 3-5 years. But you need all the money up front in order to build. So you take a short-term bridge loan to fund immediate construction, and repay the loan principal with donation installments as they come in. But that's just the principal. TCU, not Athletics, pays the loan costs and all the interest.