Is it true that opening up a new credit card account will jump your credit score 20 points?

That is simply something that is completely untrue. Credit Scores are driven off multiple factor. I am a credit analyst for a major credit card company and I hear so many misconceptions about credit that I can't help but to laugh at some of them.
Opening, Closing, paying credit cards off, charging balance onto the car, obtaining an installment loan (like a mortgage, car or personal loan) all affect everyone differently based on how loan you've had credit, how much debt you currently have, how many recent inquiries for credit, the average age of the accounts that are already open, the time since you last opened an account, how many open accounts you have, how many open but inactive accounts you have, if you have any delinquent account such as medical collections, utility collections, or late pays or charges off on you current credit report. Ehat it boils down to is that nothing with affect 2 different people the same way when it comes to credit because even though all the history could be the same there will always be slight various that will change it up for most people.
As an example...I recently opened a new credit card with a $15,000 limit and transferred $9000 to the account and paid off all of my other credit cards, however even though I had a high credit limit and paid off other card rather than adding debt my score dropped by 30 points...due to the inquiry to get the account open, the adding of the account to the credit report and then the balance...that is what really made it hurt...the account was new and new accounts with balance in excess of 50 percent of the credit line tend to have a huge impact on credit scores.
However, I have know people that had 3 or 4 cards completely maxed out to the limit and opened a new account and transferred the balance and there scores went up because they weren't as maxed out on the other accounts any more.
Best thing to do...get a copy of you credit report and score before and after the account is opened and compare the information.