The chance of getting accepted is:
1-(Chance of rejection at USF)(Chance of rejection at FSU)(Chance of rejection at Miami)(Chance of rejection at FAU)
Using Zeke's assumption that you have a 2/3 of being accepted at each place, your chances are 1-(1/3)^4= 0.98765
nota bene: This calculation assumes that each event is independent, which is obviously not a fair assumption. Unfortunately this is the best you can do with statistics.
If it were me I would probably hold onto the DO acceptance just in case, but I am extremely risk averse.
I'm not going to attempt any sort of statistical analysis. I'll leave that for the pros. What I will say......
At least at USF, they rarely reject an interviewee. Chances are that if you don't get outright acceptance you'll be placed somewhere on their waitlist. Chances are that even if you are one of the last people to interview, if you present a strong front you have a high chance of getting high tier waitlist (top 1/3 of candidates on waitlist). If you are in tier 1 of the waitlist you have an extremely high probability of getting accepted sometime between mid May to June though sometimes it may be even earlier.