No, you can not go from OCA 7 directly to OCP 8.
You can go from OCA 7 to OCP 7 to OCP 8, however it's my understanding that the OCP tests are much more difficult when compared to the OCA tests.
Given that it would probably be wiser to go from OCA 7 to OCA 8 to OCP 8. Same amount of tests, but an easier path to take.
Or, you can bypass the OCA 7 and just start at OCA 8 after which go for OCP 8.
“The strongest of all warriors are these two — Time and Patience.” ― Leo Tolstoy, War and Peace