If the Blazers Buy Out Steve Francis, Could They Sign Rashard Lewis?

No.

According to Larry Koon's exhaustive NBA salary cap FAQ (available here: http://members.cox.net/lmcoon/salarycap.htm#1), if the Blazers bought out Steve Francis' contract, the total amount of the buyout would count against the salary cap spread over the remaining term of the contract. Francis has two years left on his deal, at $33.5 million. If he agreed to a buyout for $20 million, he would count against Portland's cap at $10 million for each of the next two seasons. Such a buy-out would save Paul Allen some salary and some luxury tax, but would not get the Blazers under the salary cap (by my calculation, the Blazers' cap total would be around $57 million if they renounced Travis Outlaw, Ime Udoka and Jamal Magloire, and Francis agreed to a $20 million buy-out - the NBA salary cap was $53 million last year). So even with a buy-out, the Blazers will not be able to sign a free agent for more than the mid-level exception.

I'm making the assumption here that Francis isn't going to take less than $20 million. Unless his market value is $13.5 million (or more) over two seasons, he would lose money by taking a $20 million buy-out.

From Larry Koon's FAQ:

http://members.cox.net/lmcoon/salarycap.htm#59

How do buy-outs affect a team's salary cap?

The agreed-upon buy-out amount (see question number 59) is included in the team salary instead of the salary called for in the contract. If the player had more than one season left on his contract, then the buy-out money is distributed among those seasons in proportion to the original salary. For example, say a player had three seasons remaining on his contract, with salaries of $10 million, $11 million and $12 million. The player and team agree to a buyout of $15 million. The $15 million is therefore charged to the team salary over the three seasons. Since the original contract had $33 million left to be paid, and $10 million is 30.3% of $33 million, 30.3% of the $15 million buyout, or $4.545 million, is included in the team salary in the first season following the buyout. Likewise, 33.33% of $15 million, or $5 million, is included in the team salary in the second season, and 36.36% of $15 million, or $5.455 million, is included in the team salary in the third season.The distribution of the buy-out money is a matter of individual negotiation. Changing the number of years in which the money is paid does not change the number of years in which the team's team salary is charged. In the above example in which the player's contract is bought out with three seasons remaining, the buyout amount is always charged to the team salary over three seasons. It does not matter if the player is actually paid in a lump sum or over 20 years (a spread provision).