It depends. There are many Pennsylvania online casinos that accept credit cards. As a general rule, Visa and Mastercard are usually the brands of choice, although American Express and other credit companies can sometimes appear as an option.
The problem with depositing into one of these sites may actually depend on your bank, rather than the casino itself. Several banks, including large operators like Bank of America, Wells Fargo, and Chase, have established a policy of not allowing deposits to online gambling merchants.
Even if you do happen to have a card from a bank that will accept deposits to a gambling site, the bank may still consider the deposit to be a cash advance. Cash advance fees on credit cards can sometimes be quite painful to pay.
For PayPal, things are a little easier to manage. Most PayPal users will be able to adapt their accounts to make deposits with the service. However, take a moment to check on the fees attached with such a transaction before you send it through.